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Sample records for platelet activation status

  1. Increased platelet activation in early symptomatic versus asymptomatic carotid stenosis and relationship with microembolic status: Results from the Platelets And Carotid Stenosis (PACS) Study.

    LENUS (Irish Health Repository)

    Kinsella, Ja

    2013-04-26

    BACKGROUND: Cerebral microembolic signals (MES) may predict increased stroke risk in carotid stenosis. However, the relationship between platelet counts or platelet activation status and MES in symptomatic versus asymptomatic carotid stenosis has not been comprehensively assessed. SETTING: University teaching hospitals. METHODS: This prospective, pilot observational study assessed platelet counts and platelet activation status, and the relationship between platelet activation and MES in asymptomatic versus early (≤4 weeks after TIA\\/stroke) and late phase (≥3 months) symptomatic moderate or severe (≥50%) carotid stenosis patients. Full blood count measurements were performed, and whole blood flow cytometry was used to quantify platelet surface activation marker expression (CD62P and CD63) and circulating leucocyte-platelet complexes. Bilateral simultaneous transcranial Doppler ultrasound monitoring of the middle cerebral arteries was performed for 1 hour to classify patients as MES-positive or MES-negative. RESULTS: Data from 31 asymptomatic patients were compared with 46 symptomatic patients in the early phase, and 35 of these patients followed up to the late phase after symptom onset. The median platelet count (211 vs. 200 x 10(9) \\/L; p=0.03) and the median% lymphocyte-platelet complexes were higher in early symptomatic than asymptomatic patients (2.8 vs. 2.4%, p=0.001). The% lymphocyte-platelet complexes was higher in early symptomatic than asymptomatic patients with ≥70% carotid stenosis (p=0.0005), and in symptomatic patients recruited within 7 days of symptom onset (p=0.028). Complete TCD data were available in 25 asymptomatic and 31 early phase symptomatic, and 27 late phase symptomatic patients. 12% of asymptomatic versus 32% of early phase symptomatic (p=0.02) and 19% of late phase symptomatic patients (p=0.2) were MES-positive. Early symptomatic MES-negative patients had a higher% lymphocyte-platelet complexes than asymptomatic MES

  2. Cisplatin triggers platelet activation.

    Science.gov (United States)

    Togna, G I; Togna, A R; Franconi, M; Caprino, L

    2000-09-01

    Clinical observations suggest that anticancer drugs could contribute to the thrombotic complications of malignancy in treated patients. Thrombotic microangiopathy, myocardial infarction, and cerebrovascular thrombotic events have been reported for cisplatin, a drug widely used in the treatment of many solid tumours. The aim of this study is to explore in vitro cisplatin effect on human platelet reactivity in order to define the potentially active role of platelets in the pathogenesis of cisplatin-induced thrombotic complications. Our results demonstrate that cisplatin increases human platelet reactivity (onset of platelet aggregation wave and thromboxane production) to non-aggregating concentrations of the agonists involving arachidonic acid metabolism. Direct or indirect activation of platelet phospholipase A(2) appears to be implicated. This finding contributes to a better understanding of the pathogenesis of thrombotic complications occurring during cisplatin-based chemotherapy.

  3. Complement Activation Alters Platelet Function

    Science.gov (United States)

    2015-12-01

    Award Number: W81XWH-12-1-0523 TITLE: Complement Activation Alters Platelet Function PRINCIPAL INVESTIGATOR: George Tsokos, M.D. CONTRACTING...Activation Alters Platelet Function 5a. CONTRACT NUMBER 5b. GRANT NUMBER W81XWH-12-1-0523 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) George Tsokos, M.D...a decreased level of disease. Further studies will expand upon these observations better outlining the function of platelets in the injury associated

  4. Platelet activation determines the severity of thrombocytopenia in dengue infection

    Science.gov (United States)

    Ojha, Amrita; Nandi, Dipika; Batra, Harish; Singhal, Rashi; Annarapu, Gowtham K.; Bhattacharyya, Sankar; Seth, Tulika; Dar, Lalit; Medigeshi, Guruprasad R.; Vrati, Sudhanshu; Vikram, Naval K.; Guchhait, Prasenjit

    2017-01-01

    Thrombocytopenia is common in patients with dengue virus (DENV) infections. With a focus on understanding the possible mechanism of thrombocytopenia in DENV infections we described a direct correlation between activation and depletion of platelets in patients. Our data showed a sharp decrease in platelet counts at day 4 of fever in patients. The high DENV genome copies in platelets correlated directly with the elevated platelet activation along with increased binding of complement factor C3 and IgG on their surface at day 4. Recovery in platelet count was observed on day 10 through day 6 and 8 with simultaneous decrease in platelet activation markers. Further, our in vitro data supported the above observations describing a concentration-dependent increase in platelet activation by DENV serotype-2. The high copy number of DENV2 genome in the platelet pellet correlated directly with platelet activation, microparticle generation and clot formation. Furthermore the DENV2-activated platelets were phagocytosed in large numbers by the monocytes. The DENV2-mediated lysis and clearance of platelets were abrogated in presence of platelet activation inhibitor, prostacyclin. These observations collectively suggest that platelet activation status is an important determinant of thrombocytopenia in dengue infections. A careful strategy of inactivation of platelets may rescue them from rapid destruction during DENV infections. PMID:28139770

  5. Platelet activation and aggregation

    DEFF Research Database (Denmark)

    Jensen, Maria Sander; Larsen, O H; Christiansen, Kirsten

    2013-01-01

    This study introduces a new laboratory model of whole blood platelet aggregation stimulated by endogenously generated thrombin, and explores this aspect in haemophilia A in which impaired thrombin generation is a major hallmark. The method was established to measure platelet aggregation initiated...

  6. Platelet surface glutathione reductase-like activity.

    Science.gov (United States)

    Essex, David W; Li, Mengru; Feinman, Richard D; Miller, Anna

    2004-09-01

    We previously found that reduced glutathione (GSH) or a mixture of GSH/glutathione disulfide (GSSG) potentiated platelet aggregation. We here report that GSSG, when added to platelets alone, also potentiates platelet aggregation. Most of the GSSG was converted to GSH by a flavoprotein-dependent platelet surface mechanism. This provided an appropriate redox potential for platelet activation. The addition of GSSG to platelets generated sulfhydryls in the beta subunit of the alpha(IIb)beta(3) fibrinogen receptor, suggesting a mechanism for facilitation of agonist-induced platelet activation.

  7. Evidence of platelet activation in multiple sclerosis

    Directory of Open Access Journals (Sweden)

    Alexander J Steven

    2008-06-01

    Full Text Available Abstract Objective A fatality in one multiple sclerosis (MS patient due to acute idiopathic thrombocytopenic purpura (ITP and a near fatality in another stimulated our interest in platelet function abnormalities in MS. Previously, we presented evidence of platelet activation in a small cohort of treatment-naive MS patients. Methods In this report, 92 normal controls and 33 stable, untreated MS patients were studied. Platelet counts, measures of platelet activation [plasma platelet microparticles (PMP, P-selectin expression (CD62p, circulating platelet microaggragtes (PAg], as well as platelet-associated IgG/IgM, were carried out. In addition, plasma protein S activity was measured. Results Compared to controls, PMP were significantly elevated in MS (p Conclusion Platelets are significantly activated in MS patients. The mechanisms underlying this activation and its significance to MS are unknown. Additional study of platelet activation and function in MS patients is warranted.

  8. [Protein kinase C activation induces platelet apoptosis].

    Science.gov (United States)

    Zhao, Li-Li; Chen, Meng-Xing; Zhang, Ming-Yi; Dai, Ke-Sheng

    2013-10-01

    Platelet apoptosis elucidated by either physical or chemical compound or platelet storage occurs wildly, which might play important roles in controlling the numbers and functions of circulated platelets, or in the development of some platelet-related diseases. However, up to now, a little is known about the regulatory mechanisms of platelet apoptosis. Protein kinase C (PKC) is highly expressed in platelets and plays central roles in regulating platelet functions. Although there is evidence indicating that PKC is involved in the regulation of apoptosis of nucleated cells, it is still unclear whether PKC plays a role in platelet apoptosis. The aim of this study was to investigate the role of PKC in platelet apoptosis. The effects of PKC on mitochondrial membrane potential (ΔΨm), phosphatidylserine (PS) exposure, and caspase-3 activation of platelets were analyzed by flow cytometry and Western blot. The results showed that the ΔΨm depolarization in platelets was induced by PKC activator in time-dependent manner, and the caspase-3 activation in platelets was induced by PKC in concentration-dependent manner. However, the platelets incubated with PKC inhibitor did not results in ΔΨm depolarization and PS exposure. It is concluded that the PKC activation induces platelet apoptosis through influencing the mitochondrial functions and activating caspase 3. The finds suggest a novel mechanism for PKC in regulating platelet numbers and functions, which has important pathophysiological implications for thrombosis and hemostasis.

  9. Calpain Activator Dibucaine Induces Platelet Apoptosis

    Directory of Open Access Journals (Sweden)

    Jun Liu

    2011-03-01

    Full Text Available Calcium-dependent calpains are a family of cysteine proteases that have been demonstrated to play key roles in both platelet glycoprotein Ibα shedding and platelet activation and altered calpain activity is associated with thrombotic thrombocytopenic purpura. Calpain activators induce apoptosis in several types of nucleated cells. However, it is not clear whether calpain activators induce platelet apoptosis. Here we show that the calpain activator dibucaine induced several platelet apoptotic events including depolarization of the mitochondrial inner transmembrane potential, up-regulation of Bax and Bak, down-regulation of Bcl-2 and Bcl-XL, caspase-3 activation and phosphatidylserine exposure. Platelet apoptosis elicited by dibucaine was not affected by the broad spectrum metalloproteinase inhibitor GM6001. Furthermore, dibucaine did not induce platelet activation as detected by P-selectin expression and PAC-1 binding. However, platelet aggregation induced by ristocetin or α-thrombin, platelet adhesion and spreading on von Willebrand factor were significantly inhibited in platelets treated with dibucaine. Taken together, these data indicate that dibucaine induces platelet apoptosis and platelet dysfunction.

  10. Does bipolar pacemaker current activate blood platelets?

    DEFF Research Database (Denmark)

    Gjesdal, Grunde; Hansen, Annebirthe Bo; Brandes, Axel

    2009-01-01

    OBJECTIVE: The aim of this study was to investigate whether bipolar pacemaker current lead can activate blood platelets. The null hypothesis was that 1 minute of electrical stimulation of platelets would not influence their subsequent reactivity to adenosine diphosphate (ADP). BACKGROUND: Both...... platelets and muscle cells contain actin and myosin filaments, and both cells are activated following calcium influx. Muscle cells open their calcium channels and contract when exposed to an electric current. Current through a bipolar pacemaker lead will expose a small volume of blood, including platelets...

  11. Activation of human platelets by misfolded proteins

    NARCIS (Netherlands)

    Herczenik, E.; Bouma, B.; Korporaal, J.A.; Strangi, R.; Zeng, Q.; Gros, P.; van Eck, M.; van Berkel, T.J.C.; Gebbink, M.F.B.G.; Akkerman, J.W.N.

    2007-01-01

    Objective: Protein misfolding diseases result from the deposition of insoluble protein aggregates that often contain fibrils called amyloid. Amyloids are found in Alzheimer disease, atherosclerosis, diabetes mellitus, and systemic amyloidosis,which are diseases where platelet activation might be

  12. Platelet-mediated cytotoxicity and its enhancement by platelet activating factor.

    Science.gov (United States)

    Bykovskaya, S N; Bolvacheva, A V; Kiselevsky, M V; Khaylenko, V A; Bykovsky, A F

    1991-01-01

    Platelet cytotoxicity was assessed in 70 cancer patients with various tumor localizations and in 30 normal donors. The data presented reveal that the ACL cell line displays the highest sensitivity to platelet cytotoxicity. Using the ACL cells, we discovered that platelets from oncological patients and normal donors display comparable cytotoxicity. The level of platelet lytic activity is irrelevant to tumor localisation; however, it appears to be dependent on the stage of tumor growth. Incubation of platelets, both from donors and patients, with PAF (concentration range 10 pM to 10 nM) results in a significant rise of the killing activity of platelets. PAF induces greater cytotoxicity enhancement for platelets with lower initial activity, this pattern appearing to be the specific feature of the PAF mediated effect. Hence, platelets can be considered as effector cells relevant to antitumor immunity; PAF-mediated enhancement of platelet cytotoxicity can appear to be useful in the search for new immunotherapeutic drugs.

  13. Platelet activation patterns in platelet size sub-populations: differential responses to aspirin in vitro.

    Science.gov (United States)

    Mangalpally, Kiran Kumar R; Siqueiros-Garcia, Alan; Vaduganathan, Muthiah; Dong, Jing-Fei; Kleiman, Neal S; Guthikonda, Sasidhar

    2010-10-01

    Circulating platelets are heterogeneous in size and structure. Whether this translates into differences in platelet function and efficacy of antiplatelet therapy is unclear. Hence, we decided to investigate the activation patterns among different platelet populations differentiated by size, and to compare the inhibitory effects of aspirin in these populations. Circulating platelets from 9 healthy volunteers were separated by size and stratified into the largest and smallest quintiles. Platelets were stimulated with 75 μM arachidonic acid (AA), 10 μM ADP or 25 μM TRAP. Alpha-granule protein secretion and expression (P-selectin, VWF, fibrinogen), surface-protein activation (activated integrin αIIbβ3) were assessed. Platelet thromboxane B(2) (TxB(2)) synthesis following AA stimulation was measured in vitro before and after incubation with 265 μM aspirin. Reticulated (juvenile) platelets were assessed using thiazole orange staining. A greater number of large platelets in the largest quintile were reticulated compared with the smallest quintile (6.1 ± 2.8% vs. 1.2 ± 1.5% respectively, p aspirin (1029 ± 190 pg/mL vs. 851 ± 159 pg/mL, respectively, p = 0.03). After stimulation with each agonist, a greater proportion of large platelets bound fibrinogen, VWF, P-selectin and activated integrin αIIbβ3 than small platelets both in the presence and in the absence of in vitro aspirin. In an in vitro setting, large platelets appear to be more active than small platelets and continue to be more active even after in vitro aspirin. Platelets exhibit heterogeneity in size and structure. Whether this translates into platelet function and efficacy of antiplatelet therapy is unclear. We evaluated platelet functional properties and the effects of aspirin on separated platelet subpopulations in an in vitro setting. Platelets were sorted into the largest and smallest size quintiles using flow cytometry forward scatter. Alpha-granule protein release, dense granule content

  14. Equid herpesvirus type 1 activates platelets.

    Directory of Open Access Journals (Sweden)

    Tracy Stokol

    Full Text Available Equid herpesvirus type 1 (EHV-1 causes outbreaks of abortion and neurological disease in horses. One of the main causes of these clinical syndromes is thrombosis in placental and spinal cord vessels, however the mechanism for thrombus formation is unknown. Platelets form part of the thrombus and amplify and propagate thrombin generation. Here, we tested the hypothesis that EHV-1 activates platelets. We found that two EHV-1 strains, RacL11 and Ab4 at 0.5 or higher plaque forming unit/cell, activate platelets within 10 minutes, causing α-granule secretion (surface P-selectin expression and platelet microvesiculation (increased small events double positive for CD41 and Annexin V. Microvesiculation was more pronounced with the RacL11 strain. Virus-induced P-selectin expression required plasma and 1.0 mM exogenous calcium. P-selectin expression was abolished and microvesiculation was significantly reduced in factor VII- or X-deficient human plasma. Both P-selectin expression and microvesiculation were re-established in factor VII-deficient human plasma with added purified human factor VIIa (1 nM. A glycoprotein C-deficient mutant of the Ab4 strain activated platelets as effectively as non-mutated Ab4. P-selectin expression was abolished and microvesiculation was significantly reduced by preincubation of virus with a goat polyclonal anti-rabbit tissue factor antibody. Infectious virus could be retrieved from washed EHV-1-exposed platelets, suggesting a direct platelet-virus interaction. Our results indicate that EHV-1 activates equine platelets and that α-granule secretion is a consequence of virus-associated tissue factor triggering factor X activation and thrombin generation. Microvesiculation was only partly tissue factor and thrombin-dependent, suggesting the virus causes microvesiculation through other mechanisms, potentially through direct binding. These findings suggest that EHV-1-induced platelet activation could contribute to the thrombosis

  15. LDL oxidation by platelets propagates platelet activation via an oxidative stress-mediated mechanism.

    Science.gov (United States)

    Carnevale, Roberto; Bartimoccia, Simona; Nocella, Cristina; Di Santo, Serena; Loffredo, Lorenzo; Illuminati, Giulio; Lombardi, Elisabetta; Boz, Valentina; Del Ben, Maria; De Marco, Luigi; Pignatelli, Pasquale; Violi, Francesco

    2014-11-01

    Platelets generate oxidized LDL (ox-LDL) via NOX2-derived oxidative stress. We investigated if once generated by activated platelets ox-LDL can propagate platelet activation. Experiments were performed in platelets from healthy subjects (HS), hyper-cholesterolemic patients and patients with NOX2 hereditary deficiency. Agonist-stimulated platelets from HS added with LDL were associated with a dose-dependent increase of reactive oxidant species and ox-LDL. Agonist-stimulated platelets from HS added with a fixed dose of LDL (57.14 μmol/L) or added with homogenized human atherosclerotic plaque showed enhanced ox-LDL formation (approximately +50% and +30% respectively), which was lowered by a NOX2 inhibitor (approximately -35% and -25% respectively). Compared to HS, ox-LDL production was more pronounced in agonist-stimulated platelet rich plasma (PRP) from hyper-cholesterolemic patients but was almost absent in PRP from NOX2-deficient patients. Platelet aggregation and 8-iso-PGF2α-ΙΙΙ formation increased in LDL-treated washed platelets (+42% and +53% respectively) and PRP (+31% and +53% respectively). Also, LDL enhanced platelet-dependent thrombosis at arterial shear rate (+33%) but did not affect platelet activation in NOX2-deficient patients. Platelet activation by LDL was significantly inhibited by CD36 or LOX1 blocking peptides, two ox-LDL receptor antagonists, or by a NOX2 inhibitor. LDL-added platelets showed increased p38MAPK (+59%) and PKC (+51%) phosphorylation, p47(phox) translocation to platelet membrane (+34%) and NOX2 activation (+30%), which were inhibited by ox-LDL receptor antagonists. Platelets oxidize LDL, which in turn amplify platelet activation via specific ox-LDL receptors; both effects are mediated by NOX2 activation. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

  16. Platelet activation, function, and reactivity in atherosclerotic carotid artery stenosis: a systematic review of the literature.

    LENUS (Irish Health Repository)

    Kinsella, J A

    2012-09-27

    An important proportion of transient ischemic attack or ischemic stroke is attributable to moderate or severe (50-99%) atherosclerotic carotid stenosis or occlusion. Platelet biomarkers have the potential to improve our understanding of the pathogenesis of vascular events in this patient population. A detailed systematic review was performed to collate all available data on ex vivo platelet activation and platelet function\\/reactivity in patients with carotid stenosis. Two hundred thirteen potentially relevant articles were initially identified; 26 manuscripts met criteria for inclusion in this systematic review. There was no consistent evidence of clinically informative data from urinary or soluble blood markers of platelet activation in patients with symptomatic moderate or severe carotid stenosis who might be considered suitable for carotid intervention. Data from flow cytometry studies revealed evidence of excessive platelet activation in patients in the early, sub-acute, or late phases after transient ischemic attack or stroke in association with moderate or severe carotid stenosis and in asymptomatic moderate or severe carotid stenosis compared with controls. Furthermore, pilot data suggest that platelet activation may be increased in recently symptomatic than in asymptomatic severe carotid stenosis. Excessive platelet activation and platelet hyperreactivity may play a role in the pathogenesis of first or subsequent transient ischemic attack or stroke in patients with moderate or severe carotid stenosis. Larger longitudinal studies assessing platelet activation status with flow cytometry and platelet function\\/reactivity in symptomatic vs. asymptomatic carotid stenosis are warranted to improve our understanding of the mechanisms responsible for transient ischemic attack or stroke.

  17. Platelet antibodies, activated platelets and serum leptin in childhood immune thrombocytopenic purpura.

    Science.gov (United States)

    Badrawy, Hosny; Elsayh, Khalid I; Zahran, Asmaa M; El-Ghazali, Mohamad Hamdy

    2013-01-01

    The aim of this study was to evaluate the levels of platelet-associated antibodies (PAIgG and PAIgM), activated platelets and serum leptin in children with acute immune thrombocytopenic purpura (ITP). The study included 40 patients with ITP and 40 healthy age- and sex-matched controls. PAIgG, PAIgM and activated platelet levels were estimated by flow cytometry, and serum leptin levels were estimated by ELISA. Activated platelets and serum leptin were significantly higher in the ITP patients than in the controls. The percentage and mean fluorescence intensity of PAIgG and PAIgM staining were significantly higher in the patients than in the controls. Serum leptin and activated platelet levels in patients with thrombocytopenia of brief duration were significantly lower than those in patients with thrombocytopenia of prolonged duration. The levels of activated platelets, serum leptin and PAIgG were positively correlated, and the levels of serum leptin, activated platelets and platelet counts were negatively correlated. The increased levels of activated platelets, serum leptin and platelet-associated antibodies in children with acute ITP suggest that these factors could play a role in ITP pathogenesis. Additionally, activated platelets and serum leptin could have prognostic significance in paediatric acute ITP. Copyright © 2013 S. Karger AG, Basel.

  18. Epithelial sodium channel modulates platelet collagen activation.

    Science.gov (United States)

    Cerecedo, Doris; Martínez-Vieyra, Ivette; Alonso-Rangel, Lea; Benítez-Cardoza, Claudia; Ortega, Arturo

    2014-03-01

    Activated platelets adhere to the exposed subendothelial extracellular matrix and undergo a rapid cytoskeletal rearrangement resulting in shape change and release of their intracellular dense and alpha granule contents to avoid hemorrhage. A central step in this process is the elevation of the intracellular Ca(2+) concentration through its release from intracellular stores and on throughout its influx from the extracellular space. The Epithelial sodium channel (ENaC) is a highly selective Na(+) channel involved in mechanosensation, nociception, fluid volume homeostasis, and control of arterial blood pressure. The present study describes the expression, distribution, and participation of ENaC in platelet migration and granule secretion using pharmacological inhibition with amiloride. Our biochemical and confocal analysis in suspended and adhered platelets suggests that ENaC is associated with Intermediate filaments (IF) and with Dystrophin-associated proteins (DAP) via α-syntrophin and β-dystroglycan. Migration assays, quantification of soluble P-selectin, and serotonin release suggest that ENaC is dispensable for migration and alpha and dense granule secretion, whereas Na(+) influx through this channel is fundamental for platelet collagen activation.

  19. Xanthohumol, a Prenylated Flavonoid from Hops (Humulus lupulus), Prevents Platelet Activation in Human Platelets

    OpenAIRE

    Ye-Ming Lee; Kuo-Hsien Hsieh; Wan-Jung Lu; Hsiu-Chu Chou; Duen-Suey Chou; Li-Ming Lien; Joen-Rong Sheu; Kuan-Hung Lin

    2012-01-01

    Xanthohumol is the principal prenylated flavonoid in the hop plant (Humulus lupulus L.). Xanthohumol was found to be a very potent cancer chemopreventive agent through regulation of diverse mechanisms. However, no data are available concerning the effects of xanthohumol on platelet activation. The aim of this paper was to examine the antiplatelet effect of xanthohumol in washed human platelets. In the present paper, xanthohumol exhibited more-potent activity in inhibiting platelet aggregation...

  20. Kaempferol inhibits thrombosis and platelet activation.

    Science.gov (United States)

    Choi, Jun-Hui; Park, Se-Eun; Kim, Sung-Jun; Kim, Seung

    2015-08-01

    The objectives of the present study were to investigate whether kaempferol affects pro-coagulant proteinase activity, fibrin clot formation, blood clot and thrombin (or collagen/epinephrine)-stimulated platelet activation, thrombosis, and coagulation in ICR (Imprinting Control Region) mice and SD (Sprague-Dawley) rats. Kaempferol significantly inhibited the enzymatic activities of thrombin and FXa by 68 ± 1.6% and 52 ± 2.4%, respectively. Kaempferol also inhibited fibrin polymer formation in turbidity. Microscopic analysis was performed using a fluorescent conjugate. Kaempferol completely attenuated phosphorylation of extracellular signal-regulated kinase (ERK) 1/2, p38, c-Jun N-terminal kinase (JNK) 1/2, and phosphoinositide 3-kinase (PI3K)/PKB (AKT) in thrombin-stimulated platelets and delayed aggregation time (clotting) by 34.6% in an assay of collagen/epinephrine-stimulated platelet activation. Moreover, kaempferol protected against thrombosis development in 3 animal models, including collagen/epinephrine- and thrombin-induced acute thromboembolism models and an FeCl3-induced carotid arterial thrombus model. The ex vivo anticoagulant effect of kaempferol was further confirmed in ICR mice. This study demonstrated that kaempferol may be clinically useful due to its ability to reduce or prevent thrombotic challenge.

  1. Decrease in platelet activating factor stimulated phosphoinositide turnover during storage of human platelets in plasma

    Energy Technology Data Exchange (ETDEWEB)

    Carter, M.G.; Shukla, S.D. (Univ. of Missouri School of Medicine, Columbia (USA))

    1987-05-01

    Human platelet concentrate from the American Red Cross Blood Center was stored at 24{degree}C in a shaker and aliquots were taken out at time intervals aseptically. Platelet activating factor (PAF) stimulated turnover of phosphoinositide (PPI) was monitored by assaying {sup 32}P incorporation into phosphoinositides using platelet rich plasma (PRP). Platelets in PRP were incubated with 1 {times} 10{sup {minus}7} M PAF at 37{degree}C with gentle shaking and after 5 min their lipids were extracted and analysed by TLC for {sup 32}P-phosphoinositides. The percent stimulation of {sup 32}P incorporation by PAF (over control) into PPI was approximately 250, 100, 60, 25 and 20 on days 1, 2, 3, 5 and 6, respectively. This indicated a dramatic decrease in PAF responsive turnover of platelet PPI during storage. These findings have important implications in relation to PAF receptor activity and viability of platelets at different periods of storage.

  2. Flow cytometric assessment of activation of peripheral blood platelets in dogs with normal platelet count and asymptomatic thrombocytopenia.

    Science.gov (United States)

    Żmigrodzka, M; Guzera, M; Winnicka, A

    2016-01-01

    Platelets play a crucial role in hemostasis. Their activation has not yet been evaluated in healthy dogs with a normal and low platelet count. The aim of this study was to determine the influence of activators on platelet activation in dogs with a normal platelet count and asymptomatic thrombocytopenia. 72 clinically healthy dogs were enrolled. Patients were allocated into three groups. Group 1 consisted of 30 dogs with a normal platelet count, group 2 included 22 dogs with a platelet count between 100 and 200×109/l and group 3 consisted of 20 dogs with a platelet count lower than 100×109/l. Platelet rich-plasma (PRP) was obtained from peripheral blood samples using tripotassium ethylenediaminetetraacetic acid (K3-EDTA) as anticoagulant. Next, platelets were stimulated using phorbol-12-myristate-13-acetate or thrombin, stabilized using procaine or left unstimulated. The expression of CD51 and CD41/CD61 was evaluated. Co-expression of CD41/CD61 and Annexin V served as a marker of platelet activation. The expression of CD41/CD61 and CD51 did not differ between the 3 groups. Thrombin-stimulated platelets had a significantly higher activity in dogs with a normal platelet count than in dogs with asymptomatic thrombocytopenia. Procaine inhibited platelet activity in all groups. In conclusion, activation of platelets of healthy dogs in vitro varied depending on the platelet count and platelet activator.

  3. Heparanase expression upregulates platelet adhesion activity and thrombogenicity

    Science.gov (United States)

    Österholm, Cecilia; Zhang, Xiao; Hedin, Ulf; Vlodavsky, Israel; Li, Jin-Ping

    2016-01-01

    Heparanase is an endo-glucuronidase that specifically cleaves heparan sulfate (HS) and heparin polysaccharides. The enzyme is expressed at low levels in normal tissues, but is often upregulated under pathological conditions such as cancer and inflammation. Normal human platelets express exceptionally high levels of heparanase, but the functional consequences of this feature remain unknown. We investigated functional roles of heparanase by comparing the properties of platelets expressing high (Hpa-tg) or low (Ctr) levels of heparanase. Upon activation, Hpa-tg platelets exhibited a much stronger adhesion activity as compared to Ctr platelets, likely contributing to a higher thrombotic activity in a carotid thrombosis model. Furthermore, we found concomitant upregulated expression of both heparanase and CD62P (P-selectin) upon activation of mouse and human platelets. As platelets play important roles in tumor metastasis, these findings indicate contribution of the platelet heparanase to hyper-thrombotic conditions often seen in patients with metastatic cancer. PMID:27129145

  4. Enhanced platelet adhesion in essential thrombocythemia after in vitro activation

    Directory of Open Access Journals (Sweden)

    Andreas C. Eriksson

    2010-06-01

    Full Text Available Objective: Essential thrombocythemia (ET is a chronic myeloproliferative disorder characterized by elevated platelet counts and increased risk of thrombosis. Ex vivo data suggest increased platelet reactivity in agreement with the increased thrombosis risk, while in vitro tests often detect decreased platelet activity. The present study aimed to investigate adhesion of ET-platelets in vitro, which is an aspect of platelet function that has been addressed in only a few studies on ET patients. Material and Methods: The study included 30 ET patients and 14 healthy controls. Platelet adhesion was measured with a static platelet adhesion assay. Results: The main finding was that ET-platelets were more readily activated by adhesion-inducing stimuli in vitro than control platelets. This was particularly evident in elderly patients and when using multiple stimuli, such as surfaces of collagen or fibrinogen combined with addition of adenosine 5’-diphosphate or ristocetin. Such multiple stimuli resulted in adhesion above the control mean +2 standard deviations for approximately 50% of the patients.Conclusion: The results are in accordance with the concept of increased platelet activity in ET, but opposite to most other in vitro studies. We suggest that the conditions in the adhesion assay might mimic the in vivo situation regarding the presence of chronic platelet activation.

  5. Nephropathy in type 1 diabetes is associated with increased circulating activated platelets and platelet hyperreactivity

    DEFF Research Database (Denmark)

    Tarnow, Inge; Michelson, Alan D.; Barnard, Marc R.;

    2009-01-01

    Patients with diabetes mellitus (DM) have increased platelet activation compared to non-diabetic controls. Platelet hyperreactivity has been associated with adverse cardiovascular outcomes in Type 2 DM, and with diabetic nephropathy. We investigated the relationship between platelet activation...... and nephropathy in Type 1 DM. Patients with Type 1 DM and diabetic nephropathy (n = 35), age- and sex-matched Type 1 DM patients with persistent normoalbuminuria (n = 51), and healthy age- and sex-matched controls (n = 30) were studied. Platelet surface P-selectin, platelet surface activated GPIIb/IIIa, monocyte...... to 0.5 or 20 microM ADP) was higher in nephropathy patients compared with normoalbuminuric patients (P = 0.027), and non-diabetic controls (P = 0.0057). NPAs were higher in nephropathy patients compared to normoalbuminuric patients (P = 0.0088). MPAs were higher in nephropathy patients compared to non-diabetic...

  6. Platelets

    Science.gov (United States)

    ... tiny fraction of the blood volume. The principal function of platelets is to prevent bleeding. Red blood cells are ... forming a long string. This illustrates the basic function of platelets, to stick to any foreign surface and then ...

  7. Xanthohumol, a Prenylated Flavonoid from Hops (Humulus lupulus), Prevents Platelet Activation in Human Platelets.

    Science.gov (United States)

    Lee, Ye-Ming; Hsieh, Kuo-Hsien; Lu, Wan-Jung; Chou, Hsiu-Chu; Chou, Duen-Suey; Lien, Li-Ming; Sheu, Joen-Rong; Lin, Kuan-Hung

    2012-01-01

    Xanthohumol is the principal prenylated flavonoid in the hop plant (Humulus lupulus L.). Xanthohumol was found to be a very potent cancer chemopreventive agent through regulation of diverse mechanisms. However, no data are available concerning the effects of xanthohumol on platelet activation. The aim of this paper was to examine the antiplatelet effect of xanthohumol in washed human platelets. In the present paper, xanthohumol exhibited more-potent activity in inhibiting platelet aggregation stimulated by collagen. Xanthohumol inhibited platelet activation accompanied by relative [Ca(2+)](i) mobilization, thromboxane A(2) formation, hydroxyl radical (OH(●)) formation, and phospholipase C (PLC)γ2, protein kinase C (PKC), mitogen-activated protein kinase (MAPK), and Akt phosphorylation. Neither SQ22536, an inhibitor of adenylate cyclase, nor ODQ, an inhibitor of guanylate cyclase, reversed the xanthohumol-mediated inhibitory effect on platelet aggregation. Furthermore, xanthohumol did not significantly increase nitrate formation in platelets. This study demonstrates for the first time that xanthohumol possesses potent antiplatelet activity which may initially inhibit the PI3-kinase/Akt, p38 MAPK, and PLCγ2-PKC cascades, followed by inhibition of the thromboxane A(2) formation, thereby leading to inhibition of [Ca(2+)](i) and finally inhibition of platelet aggregation. Therefore, this novel role of xanthohumol may represent a high therapeutic potential for treatment or prevention of cardiovascular diseases.

  8. Xanthohumol, a Prenylated Flavonoid from Hops (Humulus lupulus, Prevents Platelet Activation in Human Platelets

    Directory of Open Access Journals (Sweden)

    Ye-Ming Lee

    2012-01-01

    Full Text Available Xanthohumol is the principal prenylated flavonoid in the hop plant (Humulus lupulus L.. Xanthohumol was found to be a very potent cancer chemopreventive agent through regulation of diverse mechanisms. However, no data are available concerning the effects of xanthohumol on platelet activation. The aim of this paper was to examine the antiplatelet effect of xanthohumol in washed human platelets. In the present paper, xanthohumol exhibited more-potent activity in inhibiting platelet aggregation stimulated by collagen. Xanthohumol inhibited platelet activation accompanied by relative [Ca2+]i mobilization, thromboxane A2 formation, hydroxyl radical (OH● formation, and phospholipase C (PLCγ2, protein kinase C (PKC, mitogen-activated protein kinase (MAPK, and Akt phosphorylation. Neither SQ22536, an inhibitor of adenylate cyclase, nor ODQ, an inhibitor of guanylate cyclase, reversed the xanthohumol-mediated inhibitory effect on platelet aggregation. Furthermore, xanthohumol did not significantly increase nitrate formation in platelets. This study demonstrates for the first time that xanthohumol possesses potent antiplatelet activity which may initially inhibit the PI3-kinase/Akt, p38 MAPK, and PLCγ2-PKC cascades, followed by inhibition of the thromboxane A2 formation, thereby leading to inhibition of [Ca2+]i and finally inhibition of platelet aggregation. Therefore, this novel role of xanthohumol may represent a high therapeutic potential for treatment or prevention of cardiovascular diseases.

  9. [Erythrocytes infected by Plasmodium falciparum activate human platelets].

    Science.gov (United States)

    Polack, B; Peyron, F; Sheick Zadiuddin, I; Kolodié, L; Ambroise-Thomas, P

    1990-01-01

    Blood platelets are involved in Plasmodium falciparum malaria pathology as shown by thrombocytopenia and increased plasma level of two alpha granule proteins: beta thromboglobulin (beta TG) and platelet factor 4 (PF4). In this study we demonstrate that Plasmodium falciparum parasitized erythrocytes activate directly the secretion of beta TG and PF4 by human platelets. This secretion is related to parasitemia and occurs immediately after contact. Treatment of parasited erythrocytes by trypsin and diffusion chamber experiments suggest that platelet activation is triggered by parasitic substances shed on erythrocyte membrane and released in the culture medium.

  10. Platelet activation indices and apolipoproteins in hypertensive patients.

    Science.gov (United States)

    Catalano, M; Belletti, S; Russo, U; Aronica, A; Carzaniga, G; Seregni, R; Libretti, A

    1988-10-01

    We have studied the platelet activation indices beta-thromboglobulin (beta-TG and platelet factor 4(PF4), triglycerides (TG), total cholesterol (TC), high-density lipoprotein (HDL), low-density lipoprotein (LDL), very-low-density lipoprotein (VLDL) and apolipoprotein (A1, A2, B, C2, C3, E) profiles of 22 untreated essential hypertensive subjects (WHO stages 1 and 2) and 22 controls, to see if there might be some causal relationship between lipoprotein abnormalities and greater platelet activation. The results showed the patients had both greater platelet activation than the controls, as demonstrated by higher plasma beta-TG levels (P less than 0.01) and lower apolipoprotein A2 levels (P less than 0.05). However there were no significant correlations between the platelet activation indices and the plasma levels of apolipoproteins, lipoproteins or lipids in either group.

  11. Low platelet monoamine oxidase activity in pathological gambling

    Energy Technology Data Exchange (ETDEWEB)

    Carrasco, J.L. [Department of Psychiatry, Centro de Salud Mental, Parla Madrid (Spain); Saiz-Ruiz, J. [Department of Psychiatry and Haematology, Hospital Ramon y Cajal, Madrid (Spain); Hollander, E. [Department of Psychiatry, Mount Sinai School of Medicine, Queens Hospital Center, New York (United States); Cesar, J. [Department of Haematology, Hospital Ramon y Cajal, Madrid (Spain); Lopez-Ibor, J.J. Jr. [Department of Psychiatry, Hospital San Carlos, Complutense University, Madrid (Spain)

    1994-12-01

    Decreased platelet monoamine oxidase (MAO) activity has been reported in association with sensation-seeking personality type and in some mental disorders associated with a lack of impulse control. Pathological gambling itself has been related with both sensation-seeking and reduced impulse control. Platelet MAO activity was investigated in 15 DSM-III-R pathological gamblers from our outpatient clinic. Gamblers had a significantly lower platelet MAO activity than a group of 25 healthy controls. The range of MAO levels in gamblers was also significantly shorter than in controls. In controls, platelet MAO levels showed the previously described negative correlations with sensation-seeking scores but not in gamblers. The findings are consistent with previous studies showing an association of low platelet MAO activity with impulse control disorders and raise some interesting therapeutic alternatives for pathological gambling. (au) (40 refs.).

  12. p38 mitogen-activated protein kinase activation during platelet storage: consequences for platelet recovery and hemostatic function in vivo.

    Science.gov (United States)

    Canault, Matthias; Duerschmied, Daniel; Brill, Alexander; Stefanini, Lucia; Schatzberg, Daphne; Cifuni, Stephen M; Bergmeier, Wolfgang; Wagner, Denisa D

    2010-03-01

    Platelets undergo several modifications during storage that reduce their posttransfusion survival and functionality. One important feature of these changes, which are known as platelet storage lesion, is the shedding of the surface glycoproteins GPIb-alpha and GPV. We recently demonstrated that tumor necrosis factor-alpha converting enzyme (TACE/ADAM17) mediates mitochondrial injury-induced shedding of adhesion receptors and that TACE activity correlates with reduced posttransfusion survival of these cells. We now confirm that TACE mediates receptor shedding and clearance of platelets stored for 16 hours at 37 degrees C or 22 degrees C. We further demonstrate that both storage and mitochondrial injury lead to the phosphorylation of p38 mitogen-activated kinase (MAPK) in platelets and that TACE-mediated receptor shedding from mouse and human platelets requires p38 MAP kinase signaling. Protein kinase C, extracellular regulated-signal kinase MAPK, and caspases were not involved in TACE activation. Both inhibition of p38 MAPK and inactivation of TACE during platelet storage led to a markedly improved posttransfusion recovery and hemostatic function of platelets in mice. p38 MAPK inhibitors had only minor effects on the aggregation of fresh platelets under static or flow conditions in vitro. In summary, our data suggest that inhibition of p38 MAPK or TACE during storage may significantly improve the quality of stored platelets.

  13. Calpain-controlled detachment of major glycoproteins from the cytoskeleton regulates adhesive properties of activated phosphatidylserine-positive platelets.

    Science.gov (United States)

    Artemenko, Elena O; Yakimenko, Alena O; Pichugin, Alexey V; Ataullakhanov, Fazly I; Panteleev, Mikhail A

    2016-02-15

    In resting platelets, adhesive membrane glycoproteins are attached to the cytoskeleton. On strong activation, phosphatidylserine(PS)-positive and -negative platelet subpopulations are formed. Platelet activation is accompanied by cytoskeletal rearrangement, although the glycoprotein attachment status in these two subpopulations is not clear. We developed a new, flow cytometry-based, single-cell approach to investigate attachment of membrane glycoproteins to the cytoskeleton in cell subpopulations. In PS-negative platelets, adhesive glycoproteins integrin αIIbβ3, glycoprotein Ib and, as shown for the first time, P-selectin were associated with the cytoskeleton. In contrast, this attachment was disrupted in PS-positive platelets; it was retained to some extent only in the small convex regions or 'caps'. It correlated with the degradation of talin and filamin observed only in PS-positive platelets. Calpain inhibitors essentially prevented the disruption of membrane glycoprotein attachment in PS-positive platelets, as well as talin and filamin degradation. With the suggestion that detachment of glycoproteins from the cytoskeleton may affect platelet adhesive properties, we investigated the ability of PS-positive platelets to resist shear-induced breakaway from the immobilized fibrinogen. Shear rates of 500/s caused PS-positive platelet breakaway, but their adhesion stability increased more than 10-fold after pretreatment of the platelets with calpain inhibitor. In contrast, the ability of PS-positive platelets to adhere to immobilized von Willebrand's factor at 100/s was low, but this was not affected by the preincubation of platelets with a calpain inhibitor. Our data suggest that calpain-controlled detachment of membrane glycoproteins is a new mechanism that is responsible for the loss of ability of the procoagulant platelets to resist detachment from thrombi by high shear stress.

  14. Effect of safflower yellow on platelet activating factor mediated platelet activation in patients with coronary heart disease

    Directory of Open Access Journals (Sweden)

    Damin Huang

    2012-06-01

    Full Text Available The platelet aggregation and 5-HT release by washed platelet from coronary heart disease patients following platelet activating factor (PAF treatment were detected by turbidimetry and O-phthalaldehyde assay. The free calcium concentration in the platelets was measured with the fura-2/AM probe fluorescent technique. Results showed safflower yellow could inhibit the PAF induced washed platelet aggregation and 5-HT release, which were in a safflor-yellow-dose dependent manner. When the PAF was 2.0×10-9 mol/L, the inhibition rate of platelet aggregation was 26.2%, 41.3%, 58.1%, 81.2%, and the inhibition rate of 5-HT release was 3.7%, 11.9%, 29.9% and 54.4% after treatment with safflower yellow at 0.21, 0.42, 0.85 and 1.69 g/L, respectively. The study concludes safflower yellow can inhibit the PAF induced platelet aggregation, 5-HT release by platelets and elevation of free calcium in platelets.

  15. Platelet activation in the postoperative period after lung transplantation

    Science.gov (United States)

    Sternberg, David I.; Shimbo, Daichi; Kawut, Steven M.; Sarkar, Joydeep; Hurlitz, Georg; D’Ovidio, Frank; Lederer, David J.; Wilt, Jessie S.; Arcasoy, Selim M.; Pinsky, David J.; D’Armiento, Jeanine M.; Sonett, Joshua R.

    2010-01-01

    Objective During lung transplantation, cells in the pulmonary parenchyma are subjected to ischemia, hypothermic storage, and reperfusion injury. Platelets, whose granular contents include adhesion receptors, chemokines, and coactivating substances that activate inflammatory and coagulant cascades, likely play a critical role in the lung allograft response to ischemia and reperfusion. The platelet response to the pulmonary allograft, however, has never been studied. Here we report significant platelet activation immediately after lung transplantation. Methods We performed a prospective cohort study comparing markers of platelet activation in patients undergoing lung transplantation and patients undergoing nontransplant thoracotomy. Plasma levels of soluble P-selectin, soluble CD40 ligand, and platelet–leukocyte conjugates were measured before surgery, after skin closure, and at 6 postoperative hours. Results Both soluble P-selectin and soluble CD40 ligand levels increased significantly after lung transplantation but not after thoracotomy. Additionally, platelet–monocyte conjugate fluorescence was significantly higher after lung transplantation than after thoracotomy alone. Conclusion These findings suggest that platelet activation is significantly increased after lung transplantation beyond that expected from the postoperative state. The increase in circulating platelet–monocyte conjugates suggests an important interaction between platelets and inflammatory cells. Further research should examine whether platelet activation affects early graft function after lung transplantation. PMID:18329493

  16. Platelet function and fibrinolytic activity following distance running.

    Science.gov (United States)

    Knudsen, J B; Brodthagen, U; Gormsen, J; Jordal, R; Nørregaard-Hansen, K; Paulev, P E

    1982-11-01

    6 long distance runners from the Danish marathon elite and 6 non-runners completed test runs of 28 and 12 km, respectively. Distance runners and non-runners showed the same responses in platelet function. We found a significant decrease in ADP induced platelet aggregability, a decreased serotonin release induced by ADP and collagen and an increase in platelet factor 4 immediately following the run. The antithrombin III levels remained constant. Euglobulin lysis time was shortened (by approximately 50%) and the plasminogen levels significantly increased. The last 2 findings indicate an equal increase in fibrinolytic activity during distance running in both groups. While short term, strenuous exercise induces platelet hyperaggregation, long term distance running induces a state of exhaustion of platelet aggregation capacity.

  17. Unaltered Angiogenesis-Regulating Activities of Platelets in Mild Type 2 Diabetes Mellitus despite a Marked Platelet Hyperreactivity

    Science.gov (United States)

    Miao, Xinyan; Zhang, Wei; Huang, Zhangsen

    2016-01-01

    Type 2 diabetes mellitus (T2DM) is associated with platelet dysfunction and impaired angiogenesis. Aim of the study is to investigate if platelet dysfunction might hamper platelet angiogenic activities in T2DM patients. Sixteen T2DM patients and gender/age-matched non-diabetic controls were studied. Flow cytometry and endothelial colony forming cell (ECFC) tube formation on matrigel were used to assess platelet reactivity and angiogenic activity, respectively. Thrombin receptor PAR1-activating peptide (PAR1-AP) induced higher platelet P-selectin expression, and evoked more rapid and intense platelet annexin V binding in T2DM patients, seen as a more rapid increase of annexin V+ platelets (24.3±6.4% vs 12.6±3.8% in control at 2 min) and a higher elevation (30.9±5.1% vs 24.3±3.0% at 8 min). However, PAR1-AP and PAR4-AP induced similar releases of angiogenic regulators from platelets, and both stimuli evoked platelet release of platelet angiogenic regulators to similar extents in T2DM and control subjects. Thus, PAR1-stimulated platelet releasate (PAR1-PR) and PAR4-PR similarly enhanced capillary-like network/tube formation of ECFCs, and the enhancements did not differ between T2DM and control subjects. Direct supplementation of platelets to ECFCs at the ratio of 1:200 enhanced ECFC tube formation even more markedly, leading to approximately 100% increases of the total branch points of ECFC tube formation, for which the enhancements were also similar between patients and controls. In conclusion, platelets from T2DM subjects are hyperreactive. Platelet activation induced by high doses of PAR1-AP, however, results in similar releases of angiogenic regulators in mild T2DM and control subjects. Platelets from T2DM and control subjects also demonstrate similar enhancements on ECFC angiogenic activities. PMID:27612088

  18. Effects of Antimalarial Tafenoquine on Blood Platelet Activity and Survival

    Directory of Open Access Journals (Sweden)

    Hang Cao

    2017-01-01

    Full Text Available Background/Aims: The 8-aminoquinoline tafenoquine has been shown to be effective against Plasmodia, Leishmania and Trypanosoma. The substance is at least in part effective by triggering apoptosis of the parasites. Moreover, tafenoquine has been shown to trigger eryptosis, the suicidal erythrocyte death characterized by cell shrinkage and cell membrane scrambling with phosphatidylserine translocation to the erythrocyte surface. The effect of tafenoquine on eryptosis is in part due to stimulation of Ca2+ entry and oxidative stress. Ca2+ entry is a critical event in the activation of blood platelets by thrombin and collagen related peptide (CRP. The present study explored, whether tafenoquine influences Ca2+ entry, activation and apoptosis of blood platelets. Methods: Platelets isolated from wild-type mice were exposed for 30 minutes to tafenoquine (2.5 µg/ml without or with an additional treatment with thrombin (0.01 U/ml or CRP (2 µg/ml or 5 µg/ml. Flow cytometry was employed to estimate cytosolic Ca2+-activity ([Ca2+]i from Fluo-3 fluorescence, platelet degranulation from P-selectin abundance, integrin activation from αIIbβ3 integrin abundance, phosphatidylserine abundance from annexin-V-binding, relative platelet volume from forward scatter, reactive oxygen species (ROS from DCF fluorescence, caspase 3 activity with an active caspase-3 Staining kit, and aggregation utilizing staining with CD9-APC and CD9-PE. Results: Both, thrombin (0.01 U/ml and CRP (2 µg/ml or 5 µg/ml, significantly increased [Ca2+]i, P-selectin abundance, active αIIbβ3 integrin, and annexin-V-binding, and both significantly decreased platelet volume, activated caspase 3 and stimulated aggregation. Administration of tafenoquine (2.5 µg/ml, 30 min significantly decreased [Ca2+]i both, in the absence and presence of thrombin and CRP. Tafenoquine significantly blunted the effect of thrombin and CRP on [Ca2+]i, P-selectin abundance, and active αIIbβ3 integrin, but

  19. Invasive pneumococcal disease leads to activation and hyperreactivity of platelets

    NARCIS (Netherlands)

    Tunjungputri, Rahajeng N.; De Jonge, Marien I.; De Greeff, Astrid; Van Selm, Saskia; Buys, Herma; Harders-Westerveen, Jose F.; Stockhofe-Zurwieden, Norbert; Urbanus, Rolf T.; de Groot, Phillip G.; Smith, Hilde E.; Van Der Ven, Andre J.; De Mast, Quirijn

    2016-01-01

    Using a novel porcine model of intravenous Streptococcus pneumoniae infection, we showed that invasive pneumococcal infections induce marked platelet activation and hyperreactivity. This may contribute to the vascular complications seen in pneumococcal infection.

  20. Invasive pneumococcal disease leads to activation and hyperreactivity of platelets

    NARCIS (Netherlands)

    Tunjungputri, Rahajeng N.; Jonge, de Marien I.; Greeff, de Astrid; Selm, van Saskia; Buys-Bergen, Herma; Harders-Westerveen, Jose F.; Stockhofe-Zurwieden, Norbert; Urbanus, Rolf T.; Groot, De Phillip G.; Smith, Hilde E.; Ven, van der Andre J.; Mast, de Quirijn

    2016-01-01

    Using a novel porcine model of intravenous Streptococcus pneumoniae infection, we showed that invasive pneumococcal infections induce marked platelet activation and hyperreactivity. This may contribute to the vascular complications seen in pneumococcal infection.

  1. Effect of Bexarotene on Platelet Activation and Apoptosis

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    Hang Cao

    2017-06-01

    Full Text Available Background/Aims: The retinoid X receptor (RXRs stimulator Bexarotene ((4-[1-(3,5,5,8,8-pentamethyl-5,6,7,8-tetrahydro-2-naphthylethynyl] benzoic acid is used for the treatment of several malignancies. Bexarotene is at least in part effective by stimulation of apoptosis of tumor cells. Moreover, Bexarotene triggers eryptosis, the suicidal death of erythrocytes. Similar to erythrocytes, blood platelets lack nuclei but are nevertheless able to enter an apoptosis-like phenotype, characterized by caspase activation, cell shrinkage and cell membrane scrambling with phospha-tidylserine translocation to the cell surface. Platelet apoptosis is triggered by increase of cytosolic Ca2+-activity ([Ca2+]i, which further leads to degranulation and integrin activation. Platelet activation and apoptosis could be elicited by thrombin or collagen related peptide (CRP. The present study explored whether treatment of platelets with bexarotene modifies platelet activation and apoptosis following exposure to thrombin or CRP. Methods: Platelets isolated from wild-type mice were exposed for 30 minutes to bexarotene (6 µg/ml without or with an additional treatment with thrombin (0.01 U/ml or CRP (2 µg/ml or 5 µg/ml. Flow cytometry was employed to estimate cytosolic Ca2+-activity ([Ca2+]i from Fluo-3 fluorescence, platelet degranulation from P-selectin abundance, integrin activation from αIIbβ3 integrin abundance, caspase activity utilizing an Active Caspase-3 Staining kit, phosphatidylserine abundance from annexin-V-binding, and relative platelet volume from forward scatter. Results: In the absence of thrombin or CRP, the administration of bexarotene slightly but significantly increased [Ca2+]i, but did not significantly modify P-selectin abundance, activated αIIbβ3 integrin, annexin-V-binding, cell volume, or caspase activity. Exposure of platelets to thrombin or CRP was followed by significant increase of [Ca2+]i, P-selectin abundance, active αIIbβ3 integrin

  2. Platelet activation through a Bi-leaflet mechanical heart valve

    Science.gov (United States)

    Hedayat, Mohammadali; Borazjani, Iman

    2016-11-01

    Platelet activation is one of the major drawbacks of the Mechanical Heart Valves (MHVs) which can increase the risk of thrombus formation in patients. The platelet activation in MHVs can be due to the abnormal shear stress during the systole, the backward leakage flow during the diastole, and the flow through the hinge region. We investigate the contribution of each of the above mechanism to the activation of platelets in MHVs by performing simulations of the flow through the MHV and in the hinge region. The large scale heart valve simulations are performed in a straight aorta using a sharp interface curvilinear immersed boundary method along with a strong-coupling algorithm under physiological flow conditions. In addition, in order to perform the simulation of hinge region the flow field boundary conditions are obtained from the largescale simulations during a whole cardiac cycle. In order to investigate the role of hinge flow on platelet activation in MHVs, a 23mm St. Jude Medical Regent valve hinge with three different gap sizes is tested along with different platelet activation models to ensure the consistency of our results with different activation models. We compare the platelet activation of the hinge region against the bulk of the flow during one cardiac cycle. This work is supported by the American Heart Association Grant 13SDG17220022, and the computational resources were partly provided by Center for Computational Research (CCR) at University at Buffalo.

  3. Sulfatides partition disabled-2 in response to platelet activation.

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    Karen E Drahos

    Full Text Available BACKGROUND: Platelets contact each other at the site of vascular injury to stop bleeding. One negative regulator of platelet aggregation is Disabled-2 (Dab2, which is released to the extracellular surface upon platelet activation. Dab2 inhibits platelet aggregation through its phosphotyrosine-binding (PTB domain by competing with fibrinogen for alphaIIbbeta3 integrin receptor binding by an unknown mechanism. METHODOLOGY/PRINCIPAL FINDINGS: Using protein-lipid overlay and liposome-binding assays, we identified that the N-terminal region of Dab2, including its PTB domain (N-PTB, specifically interacts with sulfatides. Moreover, we determined that such interaction is mediated by two conserved basic motifs with a dissociation constant (K(d of 0.6 microM as estimated by surface plasmon resonance (SPR analysis. In addition, liposome-binding assays combined with mass spectroscopy studies revealed that thrombin, a strong platelet agonist, cleaved N-PTB at a site located between the basic motifs, a region that becomes protected from thrombin cleavage when bound to sulfatides. Sulfatides on the platelet surface interact with coagulation proteins, playing a major role in haemostasis. Our results show that sulfatides recruit N-PTB to the platelet surface, sequestering it from integrin receptor binding during platelet activation. This is a transient recruitment that follows N-PTB internalization by an actin-dependent process. CONCLUSIONS/SIGNIFICANCE: Our experimental data support a model where two pools of Dab2 co-exist at the platelet surface, in both sulfatide- and integrin receptor-bound states, and their balance controls the extent of the clotting response.

  4. Influence of gold nanoparticles on platelets functional activity in vitro

    Science.gov (United States)

    Akchurin, Garif G.; Akchurin, George G.; Ivanov, Alexey N.; Kirichuk, Vyacheslav F.; Terentyuk, George S.; Khlebtsov, Boris N.; Khlebtsov, Nikolay G.

    2008-02-01

    Now in the leading biomedical centers of the world approved new technology of laser photothermal destruction of cancer cells using plasmon gold nanoparticles. Investigations of influence of gold nanoparticles on white rat platelets aggregative activity in vitro have been made. Platelet aggregation was investigated in platelet rich plasma (PRP) with help of laser analyzer 230 LA >, Russia). Aggregation inductor was ADP solution in terminal concentration 2.5 micromole (>, Russia). Gold nanoshells soluted in salt solution were used for experiments. Samples of PRP were incubated with 50 or 100 μl gold nanoshells solution in 5 minute, after that we made definition ADP induced platelet aggregation. We found out increase platelet function activity after incubation with nanoparticles solution which shown in maximum ADP-induced aggregation degree increase. Increase platelet function activity during intravenous nanoshells injection can be cause of thrombosis on patients. That's why before clinical application of cancer cell destruction based on laser photothermal used with plasmon gold nanoparticles careful investigations of thrombosis process and detail analyze of physiological blood parameters are very necessary.

  5. Exosomes: novel effectors of human platelet lysate activity

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    E Torreggiani

    2014-09-01

    Full Text Available Despite the popularity of platelet-rich plasma (PRP and platelet lysate (PL in orthopaedic practice, the mechanism of action and the effectiveness of these therapeutic tools are still controversial. So far, the activity of PRP and PL has been associated with different growth factors (GF released during platelet degranulation. This study, for the first time, identifies exosomes, nanosized vesicles released in the extracellular compartment by a number of elements, including platelets, as one of the effectors of PL activity. Exosomes were isolated from human PL by differential ultracentrifugation, and analysed by electron microscopy and Western blotting. Bone marrow stromal cells (MSC treated with three different exosome concentrations (0.6 μg, 5 μg and 50 μg showed a significant, dose-dependent increase in cell proliferation and migration compared to the control. In addition, osteogenic differentiation assays demonstrated that exosome concentration differently affected the ability of MSC to deposit mineralised matrix. Finally, the analysis of exosome protein content revealed a higher amount of basic fibroblast growth factor (bFGF, vascular endothelial growth factor (VEGF, platelet-derived growth factor (PDGF-BB and transforming growth factor beta 1 (TGF-β1 as compared to PL. In regards to RNA content, an enrichment of small RNAs in exosomes as compared to donor platelets has been found. These results suggest that exosomes consistently contribute to PL activity and could represent an advantageous nanodelivery system for cell-free regeneration therapies.

  6. The effect of centrifugation speed and time on pre-analytical platelet activation

    DEFF Research Database (Denmark)

    Söderström, Anna Cecilia; Nybo, Mads; Nielsen, Christian

    2016-01-01

    . METHODS: Citrate- and EDTA-anticoagulated blood from healthy volunteers were centrifuged at 80-10,000 g for 5-15 min to prepare plasma and platelet-rich plasma. Pre-analytical platelet activation was assessed by flow cytometric measurement of platelet P-selectin (CD62p) expression. Blood cell counts, mean...... platelet volume (MPV), immature platelet fraction (IPF), and platelet distribution width (PDW) were measured. Platelet aggregation in platelet-rich plasma induced by arachidonic acid (AA), ADP or thrombin receptor activator peptide-6 (TRAP) was tested by 96-well aggregometry. RESULTS: The median percentage...... of platelets expressing P-selectin in citrate- and EDTA-plasma centrifuged at 2000 g for 10 min were 43% [interquartile range (IQR), 38%-53%] and 56% (IQR, 31%-78%), respectively (p=0.82). Platelet-rich plasma prepared at 100-250 g for 10 min had significantly lower platelet P-selectin expression (11%-15%), p...

  7. Reduction of CTRP9, a novel anti-platelet adipokine, contributes to abnormal platelet activity in diabetic animals.

    Science.gov (United States)

    Wang, Wenqing; Lau, Wayne Bond; Wang, Yajing; Ma, Xinliang; Li, Rong

    2016-01-11

    Platelet hyper-reactivity is a crucial cause of accelerated atherosclerosis increasing risk of thrombotic vascular events in diabetic patients. The mechanisms leading to abnormal platelet activity during diabetes are complex and not fully defined. The current study attempted to clarify the role of CTRP9, a novel adiponectin paralog, in enhanced platelet activity and determined whether CTRP9 may inhibit platelet activity. Adult male C57BL/6 J mice were randomized to receive high-fat diet (HFD) or normal diet (ND). 8 weeks after HFD, animals were sacrificed, and both plasma CTRP9 and platelet aggregation were determined. HFD-fed animals increased weight gain significantly, and became hyperglycemic and hyperinsulinemic 8 weeks post-HFD. Compared to ND animals, HFD animals exhibited significantly decreased plasma CTRP9 concentration and increased platelet response to ADP, evidenced by augmented aggregation amplitude, steeper aggregation slope, larger area under the curve, and shorter lag time (P animals. Taken together, our results suggest reduced plasma CTRP9 concentration during diabetes plays a causative role in platelet hyper-activity, contributing to platelet-induced cardiovascular damage during this pathologic condition. Enhancing CTRP9 production and/or exogenous supplementation of CTRP9 may protect against diabetic cardiovascular injury via inhibition of abnormal platelet activity.

  8. Bryostatins activate protein kinase C in intact human platelets

    Energy Technology Data Exchange (ETDEWEB)

    Smith, J.B.; Tallant, E.A.; Pettit, G.R.; Wallace, R.W.

    1986-05-01

    Bryostatins, macrocyclic lactones isolated from a marine bryozoan, have antineoplastic activity in the P388 lymphocytic leukemia system. These compounds also stimulate growth in Swiss 3T3 cells, induce secretion in leukocytes, inhibit phorbol dibutyrate binding to a high affinity receptor, and activate the C-kinase in vitro. In human platelets, phorbol esters induce aggregation and activate protein kinase C, resulting in phosphorylation of a 47K protein and the 20K myosin light chain. The authors now show that bryostatin 7 (B-7) triggers platelet aggregation to the same rate and extent as phorbol 12-myristate 13-acetate (PMA). B-7 also causes the in vivo activation of the C-kinase, resulting in phosphorylation of both the 47K and the 20K proteins; the time courses and dose-responses of these B-7-induced phosphorylations were similar to those found with PMA. In addition, B-7 increases the level of /sup 32/P-incorporation into the platelet polyphosphoinositides, which also occurs in response to PMA. Bryostatin 3 (B-3), which has been shown to be much less potent than B-7 in mimicking other PMA effects, was much less effective than PMA or B-7 in inducing platelet aggregation and in stimulating /sup 32/P-incorporation into both proteins and the phosphoinositides. These results demonstrate that, intact human platelets, bryostatins mimic the phorbol esters tumor promoters and directly activate protein kinase C.

  9. Preanalytical requirements for flow cytometric evaluation of platelet activation: choice of anticoagulant.

    Science.gov (United States)

    Mody, M; Lazarus, A H; Semple, J W; Freedman, J

    1999-06-01

    Accurate assessment of in vivo or in vitro platelet activation requires optimal preanalytical conditions to prevent artefactual in vitro activation of the platelets. The choice of anticoagulant is one of the critical preanalytical conditions as anticoagulants exert different effects on the activation of platelets ex vivo. We tested the effectiveness of Diatube-H (also known as CTAD; sodium citrate, theophylline, adenosine and dipyridamole) and citrate vacutainer tubes in preventing artefactual activation of platelets and preserving functional reserve. Platelet surface expression of the CD62P (reflecting alpha granule release), CD63 (reflecting lysosomal release) and modulation of normal platelet membrane glycoproteins CD41a and CD42b, were measured in whole blood and in isolated platelets immediately after collection and at 6, 24 and 48 h after venipuncture. Samples taken into Diatube-H showed less spontaneous platelet activation than did those taken into citrate. To measure in vitro platelet functional reserve, thrombin was added as agonist to blood stored for varying periods up to 48 h. Although Diatube-H suppressed in vitro platelet activation for up to 4 h, in samples kept for 6-24 h before thrombin addition, the inhibitory effect was lost and platelets responded fully to agonist activation. Hence, Diatube-H preserved platelets and allowed for measurement of in vivo platelet activation as well as thrombin-induced in vitro platelet activation after 6-24 h, in both whole blood and isolated platelets.

  10. Platelet activation and platelet-leukocyte interaction in dogs naturally infected with Babesia rossi

    DEFF Research Database (Denmark)

    Goddard, Amelia; Leisewitz, Andrew L; Kristensen, Annemarie Thuri;

    2015-01-01

    EDTA as anticoagulant. Activated platelets and PLA formation were detected by measuring surface expression of P-selectin (CD62P) on platelets, monocytes and neutrophils. Of the Babesia-infected dogs, 29 survived and seven died. The percentage of CD62P-positive monocytes was significantly higher (P = 0.......036) in the Babesia-infected dogs (54%) than in healthy control dogs (35.3%). However, there were no significant differences between the Babesia-infected and control groups for CD62P-positive platelets (4.9% and 1.2%, respectively) and CD62P-positive neutrophils (28.3% and 17.9%, respectively). The percentage of CD62...... groups for the percentage of CD62P-positive platelets (survivors 4.8%; non-survivors 5.3%; controls 1.2%) or CD62P-positive neutrophils (survivors 31.6%; non-survivors 5.6%; controls 17.9%). In conclusion, Babesia-infected dogs, specifically dogs that survived, had a significantly increased percentage...

  11. Novel Bioactivity of Ellagic Acid in Inhibiting Human Platelet Activation

    Directory of Open Access Journals (Sweden)

    Yi Chang

    2013-01-01

    Full Text Available Pomegranates are widely consumed either as fresh fruit or in beverage form as juice and wine. Ellagic acid possesses potent antioxidative properties; it is known to be an effective phytotherapeutic agent with antimutagenic and anticarcinogenic qualities. Ellagic acid (20 to 80 μM exhibited a potent activity in inhibiting platelet aggregation stimulated by collagen; however, it did not inhibit platelet aggregation stimulated by thrombin, arachidonic acid, or U46619. Treatment with ellagic acid (50 and 80 μM significantly inhibited platelet activation stimulated by collagen; this alteration was accompanied by the inhibition of relative [Ca2+]i mobilization, and the phosphorylation of phospholipase C (PLCγ2, protein kinase C (PKC, mitogen-activated protein kinases (MAPKs, and Akt, as well as hydroxyl radical (OH● formation. In addition, ellagic acid also inhibited p38 MAPK and Akt phosphorylation stimulated by hydrogen peroxide. By contrast, ellagic acid did not significantly affect PKC activation and platelet aggregation stimulated by PDBu. This study is the first to show that, in addition to being considered a possible agent for preventing tumor growth, ellagic acid possesses potent antiplatelet properties. It appears to initially inhibit the PLCγ2-PKC cascade and/or hydroxyl radical formation, followed by decreased phosphorylation of MAPKs and Akt, ultimately inhibiting platelet aggregation.

  12. Factors Associated with Early Platelet Activation in Obese Children

    Science.gov (United States)

    García, Anel Gómez; Núñez, Guillermina García; Sandoval, Martha Eva Viveros; Castellanos, Sergio Gutierrez; Aguilar, Cleto Alvarez

    2014-01-01

    Objective To investigate the factors associated with platelet activation in obese children. Design Cross-sectional study. Setting Department of Pediatrics of Regional Hospital N∘ 1 of Mexican Institute of Social Security in Morelia, Michoacán, Mexico. Participants 79 obese and 64 non-obese children between the ages of 5 and 10 years. Main Outcomes Measures Obese children (body mass index [BMI] >85 in growth curves for Centers for Disease Control/National Center for Health Statistics), and the control group of 64 non-obese children (percentile <85), % body fat, platelet activation was assessed by sP-selectin. Other measures were leptin, uric acid (UA), von Willebrand Factor (vWF), plasminogen activator inhibitor (PAI-1), lipid profile, and glucose. Results Obese children displayed higher plasma sP-selectin, leptin, PAI-1, and vWF than non-obese children. In the univariate logistic regression analysis, leptin, vWF, UA, and high density lipoprotein (HDL), but not with PAI-1, were factors associated with platelet activation. By stepwise linear regression analysis adjusted by sex and age, the best predictor variables for platelet activation were leptin (β:0.381; t:4.665; P=0.0001), vWF (β:0.211; t:2.926; P=0.004), UA (β:0.166; t:2.146; P=0.034), and HDL (β:−0.215; t:−2.819; P=0.006). Conclusions Obese children have a higher risk of developing early platelet activation. Factors associated with platelet activation were Leptin, vWF, UA, and HDL. Further studies involving larger numbers of patients over a longer duration are needed to understand the possible molecular mechanism underlying the association between leptin, vWF, and UA and endothelial activation and/or endothelial damage/dysfunction in obese children and its influence in cardiovascular disease in adults. PMID:24415745

  13. Dabigatran reduces thrombin-induced platelet aggregation and activation in a dose-dependent manner

    DEFF Research Database (Denmark)

    Vinholt, Pernille Just; Nielsen, Christian; Söderström, Anna Cecilia

    2017-01-01

    Dabigatran is an oral anticoagulant and a reversible inhibitor of thrombin. Further, dabigatran might affect platelet function through a direct effect on platelet thrombin receptors. The aim was to investigate the effect of dabigatran on platelet activation and platelet aggregation. Healthy donor...

  14. Effects of non-surgical periodontal treatment on the L-arginine-nitric oxide pathway and oxidative status in platelets.

    Science.gov (United States)

    Siqueira, Mariana Alves de Sá; Fischer, Ricardo Guimarães; Pereira, Natália Rodrigues; Martins, Marcela Anjos; Moss, Monique Bandeira; Mendes-Ribeiro, Antônio Cláudio; Figueredo, Carlos Marcelo da Silva; Brunini, Tatiana Marlowe Cunha

    2013-06-01

    Several studies have suggested an increase of cardiovascular disease (CVD) risk on periodontitis patients. An enhancement has been demonstrated on both platelet activation and oxidative stress on periodontitis patients, which may contribute for this association. Therefore, the aim of this study was to evaluate the effects of non-surgical periodontal treatment on the l-arginine-nitric oxide (NO)-cyclic guanosine monophosphate (cGMP) pathway and oxidative status in platelets. A total of eight periodontitis patients and eight controls were included in this study. Clinical, laboratory and experimental evaluations were performed on baseline and 90 days after periodontal treatment (except for western blot analysis). The clinical periodontal evaluation included measurements of probing pocket depth (PPD), clinical attachment loss (CAL), % of sites with plaque and % of sites with bleeding on probing. We evaluated: l-[(3)H]arginine influx; nitric oxide synthase (NOS) and arginase enzymes activity and expression; expression of guanylate cyclase and phosphodiesterase-5 enzymes; cGMP levels; platelet aggregation; oxidative status through superoxide dismutase (SOD) and catalase activities, and measurement of reactive oxygen species (ROS) levels and C-reactive protein (CRP) levels. The initial results showed an activation of both l-arginine influx and via system y (+ )L associated with reduced intraplatelet cGMP levels in periodontitis patients and increased systemic levels of CRP. After periodontal treatment, there was a significant reduction of the % of sites with PPD 4-5mm, % of sites with CAL 4-5 mm, and an enhancement in cGMP levels and SOD activity. Moreover, CRP levels were reduced after treatment. Therefore, alterations in the intraplatelet l-arginine-NO-cGMP pathway and oxidant-antioxidant balance associated with a systemic inflammatory response may lead to platelet dysfunction, which may contribute to a higher risk of CVD in periodontitis.

  15. Comparative Activities of Cattle and Swine Platelet Microbicidal Proteins.

    Science.gov (United States)

    Ivanov, Iuri B; Gritsenko, Viktor A

    2009-12-01

    The bactericidal activities of cattle and swine platelet microbicidal proteins (PMPs) with their comparison with human PMP were studied. Activities of PMP were tested against Bacillus subtilis, Bacillus cereus, Staphylococcus aureus, Staphylococcus epidermidis, Micrococcus lysodeikticus and Escherichia coli. B. subtilis and B. cereus were high susceptible to PMP at very low concentrations. Of the gram-positive cocci studied, M. lysodeikticus and S. aureus were the most, and S. epidermidis the least, susceptible. E. coli was found to be relatively resistant to the lethal action of all PMP. The findings of this study confirm that the existence of antimicrobial peptides is conserved among mammalian platelets.

  16. Effect of supine exercise on platelet aggregation and fibrinolytic activity

    DEFF Research Database (Denmark)

    Dag, B; Fornitz, Gitte Gleerup; Bak, A M

    1994-01-01

    In 12 healthy young men, strenuous cycling exercise in the supine position, caused platelet aggregability to decrease and the ADP threshold to rise from 7.0 microM resting, to 9.5 exercising (P ... from 178 to 68 min, PAI-1 fell from 8.91 to 5.16 IU ml-1, and t-PA rose from 0.56 to 3.95 IU ml-1, all three values were significant to P exercise, it did not increase platelet activity as expected, but caused a modest increase...... of fibrinolytic activity. These results suggest that supine exercise will not affect the haemostatic system adversely....

  17. Cyclic nucleotides and mitogen-activated protein kinases: regulation of simvastatin in platelet activation

    Directory of Open Access Journals (Sweden)

    Hou Ssu-Yu

    2010-06-01

    Full Text Available Abstract Background 3-Hydroxy-3-methyl-glutaryl coenzyme A (HMG-CoA reductase inhibitors (statins have been widely used to reduce cardiovascular risk. These statins (i.e., simvastatin may exert other effects besides from their cholesterol-lowering actions, including inhibition of platelet activation. Platelet activation is relevant to a variety of coronary heart diseases. Although the inhibitory effect of simvastatin in platelet activation has been studied; the detailed signal transductions by which simvastatin inhibit platelet activation has not yet been completely resolved. Methods The aim of this study was to systematically examine the detailed mechanisms of simvastatin in preventing platelet activation. Platelet aggregation, flow cytometric analysis, immunoblotting, and electron spin resonance studies were used to assess the antiplatelet activity of simvastatin. Results Simvastatin (20-50 μM exhibited more-potent activity of inhibiting platelet aggregation stimulated by collagen than other agonists (i.e., thrombin. Simvastatin inhibited collagen-stimulated platelet activation accompanied by [Ca2+]i mobilization, thromboxane A2 (TxA2 formation, and phospholipase C (PLCγ2, protein kinase C (PKC, and mitogen-activated protein kinases (i.e., p38 MAPK, JNKs phosphorylation in washed platelets. Simvastatin obviously increased both cyclic AMP and cyclic GMP levels. Simvastatin markedly increased NO release, vasodilator-stimulated phosphoprotein (VASP phosphorylation, and endothelial nitric oxide synthase (eNOS expression. SQ22536, an inhibitor of adenylate cyclase, markedly reversed the simvastatin-mediated inhibitory effects on platelet aggregation, PLCγ2 and p38 MAPK phosphorylation, and simvastatin-mediated stimulatory effects on VASP and eNOS phosphorylation. Conclusion The most important findings of this study demonstrate for the first time that inhibitory effect of simvastatin in platelet activation may involve activation of the cyclic AMP

  18. Effect of combined anti-platelets drugs on platelet activation in the elderly patients with acute coronary syndrome

    Institute of Scientific and Technical Information of China (English)

    黄大海

    2012-01-01

    Objective To investigate the effect of combined anti-platelets drugs on platelet activation in the elderly patients with acute coronary syndrome(ACS).Methods Totally 72 elderly patients with ACS were divided randomly into two groups according to age ≤80 years and>80 years.

  19. Involvement of Ca2+ Activated Cl- Channel Ano6 in Platelet Activation and Apoptosis

    Directory of Open Access Journals (Sweden)

    Guoxing Liu

    2015-11-01

    Full Text Available Background/Aims: The ubiquitously expressed Ca2+ Activated Cl- Channel Ano6 participates in the stimulation of cell membrane scrambling. Defective Ano6 underlies the Scott syndrome, an inherited bleeding disorder with impaired scrambling of plasma membrane phospholipids. At least in theory, the bleeding disorder of Scott syndrome may result from impaired platelet function. Activators of platelets include thrombin and collagen related peptide (CRP, which trigger increase of cytosolic Ca2+-activity ([Ca2+]i, production of reactive oxygen species (ROS, degranulation, integrin activation, as well as cell shrinkage and phospholipid scrambling of the cell membrane. The present study thus explored whether Ano6 modifies activation-induced alterations of cytosolic Ca2+-activity ([Ca2+]i, degranulation (P-selectin exposure, integrin activation, phosphatidylserine exposure on the platelet surface and platelet volume. Methods: Platelets from mice lacking Ano6 (ano6-/- were compared to platelets from corresponding wild-type mice (ano6+/+. [Ca2+]i was estimated from Fluo-3 fluorescence, ROS from DCFDA fluorescence, degranulation from P-selectin abundance, integrin activation from αIIbβ3-integrin abundance, phosphatidylserine abundance from annexin-V-binding, and cell volume from forward scatter. Results: Platelet number in blood was slightly higher in ano6-/- mice than in ano6+/+ mice. Without activation [Ca2+]i and volume were similar in ano6-/- and ano6+/+ platelets as well as ROS abundance, P-selectin abundance, αIIbβ3 integrin activation, and phosphatidylserine exposure were negligible in both genotypes. Thrombin (0.01 U/ml and CRP (2 or 5 µg/ml increased [Ca2+]i, ROS abundance, platelet degranulation, αIIbβ3 integrin activation, and triggered annexin-V-binding as well as cell shrinkage, all effects less pronounced in ano6-/- than in ano6+/+ platelets. Conclusions: Genetic knockout of Ano6 blunts thrombin- and CRP-induced activation and apoptosis

  20. Effects of pathogen reduction systems on platelet microRNAs, mRNAs, activation, and function.

    Science.gov (United States)

    Osman, Abdimajid; Hitzler, Walter E; Meyer, Claudius U; Landry, Patricia; Corduan, Aurélie; Laffont, Benoit; Boilard, Eric; Hellstern, Peter; Vamvakas, Eleftherios C; Provost, Patrick

    2015-01-01

    Pathogen reduction (PR) systems for platelets, based on chemically induced cross-linking and inactivation of nucleic acids, potentially prevent transfusion transmission of infectious agents, but can increase clinically significant bleeding in some clinical studies. Here, we documented the effects of PR systems on microRNA and mRNA levels of platelets stored in the blood bank, and assessed their impact on platelet activation and function. Unlike platelets subjected to gamma irradiation or stored in additive solution, platelets treated with Intercept (amotosalen+ ultraviolet-A [UVA] light) exhibited significantly reduced levels of 6 of the 11 microRNAs, and 2 of the 3 anti-apoptotic mRNAs (Bcl-xl and Clusterin) that we monitored, compared with platelets stored in plasma. Mirasol (riboflavin+ UVB light) treatment of platelets did not produce these effects. PR neither affected platelet microRNA synthesis or function nor induced cross-linking of microRNA-sized endogenous platelet RNA species. However, the reduction in the platelet microRNA levels induced by Intercept correlated with the platelet activation (p platelet aggregation response to ADP (p platelet activation, resulting in the release of microRNAs and mRNAs from platelets. The clinical implications of this reduction in platelet nucleic acids secondary to Intercept remain to be established.

  1. Platelet activation by extracellular matrix proteins in haemostasis and thrombosis.

    Science.gov (United States)

    Watson, Steve P

    2009-01-01

    The prevention of excessive blood loss to avoid fatal haemorrhage is a pivotal process for all organisms possessing a circulatory system. Increased circulating blood volume and pressure, as required in larger animals, make this process all the more important and challenging. It is essential to have a powerful and rapid system to detect damage and generate an effective seal, and which is also exquisitely regulated to prevent unwanted, excessive or systemic activation so as to avoid blockage of vessels. Thus, a highly specialised and efficient haemostatic system has evolved that consists of cellular (platelets) and protein (coagulation factors) components. Importantly, this is able to support haemostasis in both the low shear environment of the venous system and the high shear environment of the arterial system. Endothelial cells, lining the entire circulation system, play a crucial role in the delicate balance between activation and inhibition of the haemostatic system. An intact and healthy endothelium supports blood flow by preventing attachment of cells and proteins which is required for initiation of coagulation and platelet activation. Endothelial cells produce and release the two powerful soluble inhibitors of platelet activation, nitric oxide and prostacyclin, and express high levels of CD39 which rapidly metabolises the major platelet feedback agonist, ADP. This antithrombotic environment however can rapidly change following activation or removal of endothelial cells through injury or rupture of atherosclerotic plaques. Loss of endothelial cells exposes the subendothelial extracellular matrix which creates strong signals for activation of the haemostatic system including powerful platelet adhesion and activation. Quantitative and qualitative changes in the composition of the subendothelial extracellular matrix influence these prothrombotic characteristics with life threatening thrombotic and bleeding complications, as illustrated by formation of

  2. Characterization and ATPase activity of human platelet actomyosin

    NARCIS (Netherlands)

    Lindemans, J.; Bouma, B.N.; Sixma, J.J.

    1974-01-01

    Platelet actomyosin, partially purified by successive precipitation had a specific viscosity of 0,15 and a sensitivity to ATP of 60 %. The enzyme preparation was separated into the actin and myosin components and some myosin fragments by SDS-polyacrylamide gel electrophoresis. The ATPase activity of

  3. Impact of smoking status on platelet function and clinical outcomes with prasugrel vs. clopidogrel in patients with acute coronary syndromes managed without revascularization

    DEFF Research Database (Denmark)

    Cornel, Jan H; Ohman, E Magnus; Neely, Benjamin;

    2014-01-01

    BACKGROUND: To further explore the impact of smoking on antiplatelet activity and treatment response, we evaluated time-dependent relationships between smoking status with on-treatment platelet reactivity and clinical outcomes for prasugrel vs. clopidogrel in patients with acute coronary syndrome...

  4. Activated platelets enhance IL-10 secretion and reduce TNF-α secretion by monocytes

    DEFF Research Database (Denmark)

    Gudbrandsdottir, Sif; Hasselbalch, Hans C; Nielsen, Claus H

    2013-01-01

    Activated platelets are known to modulate immune responses by secreting or shedding a range of immunomodulatory substances. We examined the influence of activated platelets on cytokine production by normal human mononuclear cells, induced by tetanus toxoid (TT), human thyroglobulin (TG), Escheric......Activated platelets are known to modulate immune responses by secreting or shedding a range of immunomodulatory substances. We examined the influence of activated platelets on cytokine production by normal human mononuclear cells, induced by tetanus toxoid (TT), human thyroglobulin (TG...

  5. Heat shock protein 70 regulates platelet integrin activation, granule secretion and aggregation.

    Science.gov (United States)

    Rigg, Rachel A; Healy, Laura D; Nowak, Marie S; Mallet, Jérémy; Thierheimer, Marisa L D; Pang, Jiaqing; McCarty, Owen J T; Aslan, Joseph E

    2016-04-01

    Molecular chaperones that support protein quality control, including heat shock protein 70 (Hsp70), participate in diverse aspects of cellular and physiological function. Recent studies have reported roles for specific chaperone activities in blood platelets in maintaining hemostasis; however, the functions of Hsp70 in platelet physiology remain uninvestigated. Here we characterize roles for Hsp70 activity in platelet activation and function. In vitro biochemical, microscopy, flow cytometry, and aggregometry assays of platelet function, as well as ex vivo analyses of platelet aggregate formation in whole blood under shear, were carried out under Hsp70-inhibited conditions. Inhibition of platelet Hsp70 blocked platelet aggregation and granule secretion in response to collagen-related peptide (CRP), which engages the immunoreceptor tyrosine-based activation motif-bearing collagen receptor glycoprotein VI (GPVI)-Fc receptor-γ chain complex. Hsp70 inhibition also reduced platelet integrin-αIIbβ3 activation downstream of GPVI, as Hsp70-inhibited platelets showed reduced PAC-1 and fibrinogen binding. Ex vivo, pharmacological inhibition of Hsp70 in human whole blood prevented the formation of platelet aggregates on collagen under shear. Biochemical studies supported a role for Hsp70 in maintaining the assembly of the linker for activation of T cells signalosome, which couples GPVI-initiated signaling to integrin activation, secretion, and platelet function. Together, our results suggest that Hsp70 regulates platelet activation and function by supporting linker for activation of T cells-associated signaling events downstream of platelet GPVI engagement, suggesting a role for Hsp70 in the intracellular organization of signaling systems that mediate platelet secretion, "inside-out" activation of platelet integrin-αIIbβ3, platelet-platelet aggregation, and, ultimately, hemostatic plug and thrombus formation.

  6. In vitro platelet activation, aggregation and platelet-granulocyte complex formation induced by surface modified single-walled carbon nanotubes.

    Science.gov (United States)

    Fent, János; Bihari, Péter; Vippola, Minnamari; Sarlin, Essi; Lakatos, Susan

    2015-08-01

    Surface modification of single-walled carbon nanotubes (SWCNTs) such as carboxylation, amidation, hydroxylation and pegylation is used to reduce the nanotube toxicity and render them more suitable for biomedical applications than their pristine counterparts. Toxicity can be manifested in platelet activation as it has been shown for SWCNTs. However, the effect of various surface modifications on the platelet activating potential of SWCNTs has not been tested yet. In vitro platelet activation (CD62P) as well as the platelet-granulocyte complex formation (CD15/CD41 double positivity) in human whole blood were measured by flow cytometry in the presence of 0.1mg/ml of pristine or various surface modified SWCNTs. The effect of various SWCNTs was tested by whole blood impedance aggregometry, too. All tested SWCNTs but the hydroxylated ones activate platelets and promote platelet-granulocyte complex formation in vitro. Carboxylated, pegylated and pristine SWCNTs induce whole blood aggregation as well. Although pegylation is preferred from biomedical point of view, among the samples tested by us pegylated SWCNTs induced far the most prominent activation and a well detectable aggregation of platelets in whole blood.

  7. L-amino acid oxidase from Naja atra venom activates and binds to human platelets

    Institute of Scientific and Technical Information of China (English)

    Rui Li; Shaowen Zhu; Jianbo Wu; Wanyu Wang; Qiumin Lu; Kenneth J.Clemetson

    2008-01-01

    An L-amino acid oxidase (LAAO),NA-LAAO,was purified from the venom of Naja atra.Its N-terminal sequence shows great similarity with LAAOs from other snake venoms.NALAAO dose-dependently induced aggregation of washed human platelets.However,it had no activity on platelets in platelet-rich plasma.A low concentration of NA-LAAO greatly promoted the effect of hydrogen peroxide,whereas hydrogen peroxide itself had little activation effect on platelets.NA-LAAO induced tyrosine phosphorylation of a number of platelet proteins including Src kinase,spleen tyrosine kinase,and phospholipase C γ2.Unlike convulxin,Fc receptor γ chain and T lymphocyte adapter protein are not phosphorylated in NA-LAAO activated platelets,suggesting an activation mechanism different from the glycoprotein VI pathway.Catalase inhibited the platelet aggregation and platelet protein phosphorylation induced by NA-LAAO.NA-LAAO bound to fixed platelets as well as to platelet lysates of Western blots.Furthermore,affinity chromatography of platelet proteins on an NA-LAAO Sepharose 4B column isolated a few platelet membrane proteins,suggesting that binding of NA-LAAO to the platelet membrane might play a role in its action on platelets.

  8. Platelets Mediate Host Defense against Staphylococcus aureus through Direct Bactericidal Activity and by Enhancing Macrophage Activities.

    Science.gov (United States)

    Ali, Ramadan A; Wuescher, Leah M; Dona, Keith R; Worth, Randall G

    2017-01-01

    Platelets are the chief effector cells in hemostasis. However, recent evidence suggests they have multiple roles in host defense against infection. Reports by us and others showed that platelets functionally contribute to protection against Staphylococcus aureus infection. In the current study, the capacity of mouse platelets to participate in host defense against S. aureus infection was determined by assessing two possibilities. First, we determined the ability of platelets to kill S. aureus directly; and, second, we tested the possibility that platelets enhance macrophage phagocytosis and intracellular killing of S. aureus In this study we report evidence in support of both mechanisms. Platelets effectively killed two different strains of S. aureus. A clinical isolate of methicillin-resistant S. aureus was killed by platelets (>40% killing in 2 h) in a thrombin-dependent manner whereas a methicillin-sensitive strain was killed to equal extent but did not require thrombin. Interestingly, thrombin-stimulated platelets also significantly enhanced peritoneal macrophage phagocytosis of both methicillin-resistant S. aureus and methicillin-sensitive S. aureus by >70%, and restricted intracellular growth by >40%. Enhancement of macrophage anti-S. aureus activities is independent of contact with platelets but is mediated through releasable products, namely IL-1β. These data confirm our hypothesis that platelets participate in host defense against S. aureus both through direct killing of S. aureus and enhancing the antimicrobial function of macrophages in protection against S. aureus infection. Copyright © 2016 by The American Association of Immunologists, Inc.

  9. The effect of gas plasma modification on platelet and contact phase activation processes.

    Science.gov (United States)

    Rhodes, Nicholas P; Wilson, Darren J; Williams, Rachel L

    2007-11-01

    Medical-grade polytetrafluoroethylene (PTFE), polydimethylsiloxane (PDMS), polyetherurethane (PEU) and ultrahigh molecular weight polyethylene (UHMWPE) were plasma treated with O2, Ar, N2 and NH3. Their surface properties were characterised using X-ray photoelectron spectroscopy (XPS), static secondary ion mass spectroscopy (SSIMS), atomic force microscopy (AFM) and dynamic contact angle (DCA) analysis. Platelet adhesion, aggregation, activation and release of microparticles were determined after contact with whole blood in a cone and plate viscometer. Activation of the coagulation system was quantified in a static environment using a partial thromboplastin time (PTT) assay. The chemical compositions of the untreated surfaces were found to be very similar to those of the bulk material except for PEU, whose surface was comprised almost entirely of soft ether segments. For all materials, the different plasma treatments resulted in moderate etching with the incorporation of functional groups and removal of side groups: defluorination, dehydrogenation, cleavage of methyl side groups and soft segments for PTFE, UHMWPE, PDMS and PEU, respectively. Consequently, plasma treatment resulted in increased wettability in all cases. Blood contact with the virgin materials resulted in activation of platelets and the clotting cascade. Plasma treatment resulted in a significant reduction in platelet adhesion for all materials and all treatments. In the case of PTFE and PEU, the activation status of these cells was also reduced. Plasma treatment of all materials reduced fluid-phase CD62P expression. Platelet aggregate size correlated well with degree of aggregate formation, but many treatments increased the degree of aggregation, as was the case for microparticle shedding. There was no correlation between CD62P expression, aggregate formation and platelet microparticle (PMP) shedding. It is concluded that despite incorporation of the same chemical groups, the pattern of response to

  10. Platelet-rich plasma preparation using three devices : Implications for platelet activation and platelet growth factor release

    NARCIS (Netherlands)

    Everts, Peter A. M.; Mahoney, Christine Brown; Hoffmann, Johannes J. M. L.; Schonberger, Jacques P. A. M.; Box, Henk A. M.; Van Zundert, Andre; Knape, Johannes T. A.

    2006-01-01

    Background: In this study, three commercial systems for the preparation of platelet-rich plasma (PRP) were compared and platelet growth factors release was measured. Methods: Ten healthy volunteers donated whole blood that was fractionated by a blood cell separator, and a table-top centrifuge to pre

  11. Platelet-rich plasma stimulated by pulse electric fields: Platelet activation, procoagulant markers, growth factor release and cell proliferation.

    Science.gov (United States)

    Frelinger, A L; Torres, A S; Caiafa, A; Morton, C A; Berny-Lang, M A; Gerrits, A J; Carmichael, S L; Neculaes, V B; Michelson, A D

    2016-01-01

    Therapeutic use of activated platelet-rich plasma (PRP) has been explored for wound healing, hemostasis and antimicrobial wound applications. Pulse electric field (PEF) stimulation may provide more consistent platelet activation and avoid complications associated with the addition of bovine thrombin, the current state of the art ex vivo activator of therapeutic PRP. The aim of this study was to compare the ability of PEF, bovine thrombin and thrombin receptor activating peptide (TRAP) to activate human PRP, release growth factors and induce cell proliferation in vitro. Human PRP was prepared in the Harvest SmartPreP2 System and treated with vehicle, PEF, bovine thrombin, TRAP or Triton X-100. Platelet activation and procoagulant markers and microparticle generation were measured by flow cytometry. Released growth factors were measured by ELISA. The releasates were tested for their ability to stimulate proliferation of human epithelial cells in culture. PEF produced more platelet-derived microparticles, P-selectin-positive particles and procoagulant annexin V-positive particles than bovine thrombin or TRAP. These differences were associated with higher levels of released epidermal growth factor after PEF than after bovine thrombin or TRAP but similar levels of platelet-derived, vascular-endothelial, and basic fibroblast growth factors, and platelet factor 4. Supernatant from PEF-treated platelets significantly increased cell proliferation compared to plasma. In conclusion, PEF treatment of fresh PRP results in generation of microparticles, exposure of prothrombotic platelet surfaces, differential release of growth factors compared to bovine thrombin and TRAP and significant cell proliferation. These results, together with PEF's inherent advantages, suggest that PEF may be a superior alternative to bovine thrombin activation of PRP for therapeutic applications.

  12. Mechanism of platelet activation induced by endocannabinoids in blood and plasma.

    Science.gov (United States)

    Brantl, S Annette; Khandoga, Anna L; Siess, Wolfgang

    2014-01-01

    Platelets play a central role in atherosclerosis and atherothrombosis, and circulating endocannabinoids might modulate platelet function. Previous studies concerning effects of anandamide (N-arachidonylethanolamide) and 2-arachidonoylglycerol (2-AG) on platelets, mainly performed on isolated cells, provided conflicting results. We therefore investigated the action of three main endocannabinoids [anandamide, 2-AG and virodhamine (arachidonoylethanolamine)] on human platelets in blood and platelet-rich plasma (PRP). 2-AG and virodhamine induced platelet aggregation in blood, and shape change, aggregation and adenosine triphosphate (ATP) secretion in PRP. The EC50 of 2-AG and virodhamine for platelet aggregation in blood was 97 and 160 µM, respectively. Lower concentrations of 2-AG (20 µM) and virodhamine (50 µM) synergistically induced aggregation with other platelet stimuli. Platelet activation induced by 2-AG and virodhamine resembled arachidonic acid (AA)-induced aggregation: shape change, the first platelet response, ATP secretion and aggregation induced by 2-AG and virodhamine were all blocked by acetylsalicylic acid (ASA) or the specific thromboxane A2 (TXA2) antagonist daltroban. In addition, platelet activation induced by 2-AG and virodhamine in blood and PRP were inhibited by JZL184, a selective inhibitor of monoacylglycerol lipase (MAGL). In contrast to 2-AG and virodhamine, anandamide, a substrate of fatty acid amidohydrolase, was inactive. Synthetic cannabinoid receptor subtype 1 (CB1) and 2 (CB2) agonists lacked stimulatory as well as inhibitory platelet activity. We conclude that 2-AG and virodhamine stimulate platelets in blood and PRP by a MAGL-triggered mechanism leading to free AA and its metabolism by platelet cyclooxygenase-1/thromboxane synthase to TXA2. CB1, CB2 or non-CB1/CB2 receptors are not involved. Our results imply that ASA and MAGL inhibitors will protect platelets from activation by high endocannabinoid levels, and that

  13. Can mean platelet component be used as an index of platelet activity in stable coronary artery disease?

    LENUS (Irish Health Repository)

    Cooke, John

    2012-01-31

    Acute coronary syndrome is associated with intracoronary thrombosis secondary to platelet activation. Previous groups have investigated platelet activation in both stable and unstable vascular disease. Most measures of platelet activation are not routinely available or easily adaptable to large scale clinical use. Recently, measurement of the mean platelet component (MPC) has become part of the routine data provided by an automated full blood count analyser, the Advia 120. MPC measures platelet density which changes on platelet activation. Our objectives were to determine if platelet activation, as measured by MPC, is increased in patients with stable coronary artery disease (CAD) and to determine if MPC could be useful in differentiating people with stable CAD from controls on an everyday clinical basis. Three hundred and forty-five consecutive patients attending for elective coronary angiography had full blood count analysis and MPC measurement performed using an ADVIA-120 analyser. Three hundred and twenty-four were analysed in our final dataset. Two hundred and fifty-three (78%) had CAD. Patients with CAD were significantly (p<0.001) older than those without (63.8 versus 56.0 years). Results failed to demonstrate a difference (p=0.467) in MPC between patients with CAD and those with normal coronary arteries (25.8 versus 26.0). Likewise, there was no correlation between MPC and the severity of CAD (Kendall\\'s tau b=-0.086, p=0.04). MPC is not a useful index of platelet activity in stable CAD when used in everyday clinical practice.

  14. Can mean platelet component be used as an index of platelet activity in stable coronary artery disease?

    LENUS (Irish Health Repository)

    Cooke, John

    2009-04-01

    Acute coronary syndrome is associated with intracoronary thrombosis secondary to platelet activation. Previous groups have investigated platelet activation in both stable and unstable vascular disease. Most measures of platelet activation are not routinely available or easily adaptable to large scale clinical use. Recently, measurement of the mean platelet component (MPC) has become part of the routine data provided by an automated full blood count analyser, the Advia 120. MPC measures platelet density which changes on platelet activation. Our objectives were to determine if platelet activation, as measured by MPC, is increased in patients with stable coronary artery disease (CAD) and to determine if MPC could be useful in differentiating people with stable CAD from controls on an everyday clinical basis. Three hundred and forty-five consecutive patients attending for elective coronary angiography had full blood count analysis and MPC measurement performed using an ADVIA-120 analyser. Three hundred and twenty-four were analysed in our final dataset. Two hundred and fifty-three (78%) had CAD. Patients with CAD were significantly (p<0.001) older than those without (63.8 versus 56.0 years). Results failed to demonstrate a difference (p=0.467) in MPC between patients with CAD and those with normal coronary arteries (25.8 versus 26.0). Likewise, there was no correlation between MPC and the severity of CAD (Kendall\\'s tau b=-0.086, p=0.04). MPC is not a useful index of platelet activity in stable CAD when used in everyday clinical practice.

  15. PPARγ ligands decrease hydrostatic pressure-induced platelet aggregation and proinflammatory activity.

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    Fang Rao

    Full Text Available Hypertension is known to be associated with platelet overactivity, but the direct effects of hydrostatic pressure on platelet function remain unclear. The present study sought to investigate whether elevated hydrostatic pressure is responsible for platelet activation and to address the potential role of peroxisome proliferator-activated receptor-γ (PPARγ. We observed that hypertensive patients had significantly higher platelet volume and rate of ADP-induced platelets aggregation compared to the controls. In vitro, Primary human platelets were cultured under standard (0 mmHg or increased (120, 180, 240 mmHg hydrostatic pressure for 18 h. Exposure to elevated pressure was associated with morphological changes in platelets. Platelet aggregation and PAC-1 (the active confirmation of GPIIb/IIIa binding were increased, CD40L was translocated from cytoplasm to the surface of platelet and soluble CD40L (sCD40L was released into the medium in response to elevated hydrostatic pressure (180 and 240 mmHg. The PPARγ activity was up-regulated as the pressure was increased from 120 mmHg to 180 mmHg. Pressure-induced platelet aggregation, PAC-1 binding, and translocation and release of CD40L were all attenuated by the PPARγ agonist Thiazolidinediones (TZDs. These results demonstrate that platelet activation and aggregation are increased by exposure to elevated pressure and that PPARγ may modulate platelet activation induced by high hydrostatic pressure.

  16. Echicetin coated polystyrene beads: a novel tool to investigate GPIb-specific platelet activation and aggregation.

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    Navdaev, Alexey; Subramanian, Hariharan; Petunin, Alexey; Clemetson, Kenneth J; Gambaryan, Stepan; Walter, Ulrich

    2014-01-01

    von Willebrand factor/ristocetin (vWF/R) induces GPIb-dependent platelet agglutination and activation of αIIbβ3 integrin, which also binds vWF. These conditions make it difficult to investigate GPIb-specific signaling pathways in washed platelets. Here, we investigated the specific mechanisms of GPIb signaling using echicetin-coated polystyrene beads, which specifically activate GPIb. We compared platelet activation induced by echicetin beads to vWF/R. Human platelets were stimulated with polystyrene beads coated with increasing amounts of echicetin and platelet activation by echicetin beads was then investigated to reveal GPIb specific signaling. Echicetin beads induced αIIbβ3-dependent aggregation of washed platelets, while under the same conditions vWF/R treatment led only to αIIbβ3-independent platelet agglutination. The average distance between the echicetin molecules on the polystyrene beads must be less than 7 nm for full platelet activation, while the total amount of echicetin used for activation is not critical. Echicetin beads induced strong phosphorylation of several proteins including p38, ERK and PKB. Synergistic signaling via P2Y12 and thromboxane receptor through secreted ADP and TxA2, respectively, were important for echicetin bead triggered platelet activation. Activation of PKG by the NO/sGC/cGMP pathway inhibited echicetin bead-induced platelet aggregation. Echicetin-coated beads are powerful and reliable tools to study signaling in human platelets activated solely via GPIb and GPIb-triggered pathways.

  17. Does meta-chlorophenylpiperazine (mCPP) activate human platelets?

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    Frampton, A E; Andrews, J C H; Parfitt, A; Jagroop, I A; Mikhailidis, D P; Henry, J A

    2006-02-01

    mCPP (meta-chlorophenylpiperazine), an agonist at serotonin (5-hydroxytryptamine, 5-HT) 5-HT2 receptors, has been used as a probe of serotonergic function. We assessed its effect on platelet activation by measuring median platelet volume (MPV), the Sonoclot (SCT) pattern and plasma and intraplatelet serotonin. (a) In vitro study: MPV was measured (n = 7) using a high-resolution channelyzer: Saline (median and range (5.23 fl; 5.10-6.18) vs. mCPP (5.36; 5.10-6.44) P = 0.03; ADP (5.42; 5.29-6.44) vs. ADP + mCPP (5.67; 5.42-6.63) P = 0.02; mCPP (5.36; 5.10-6.44) vs. ADP + mCPP (5.67; 5.42-6.63) P = 0.02. Therefore, mCPP increases the MPV and enhances the effect of ADP. (b) In vivo study: The SCT time to inflection (TI) and time to peak (TP) were measured following the oral administration of mCPP (0.5 mg/kg) or aspirin (300 mg) (n = 10). Ingestion of mCPP significantly shortened TI and TP indicating platelet activation. TI: 0 h (mean +/- SD: 10.2 +/- 2.0 min) vs. 6 h (9.3 +/- 1.5) P = 0.03; TP: 0 h (31.9 +/- 7.6) vs. 6 h (23.1 +/- 2.9) P = 0.01. Aspirin had no effect on TI or TP. There were no significant changes in plasma and intraplatelet 5-HT. It is concluded that mCPP activates human platelets via 5-HT receptors.

  18. Platelet Activation in Human Immunodeficiency Virus Type-1 Patients Is Not Altered with Cocaine Abuse.

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    Michelle Kiebala

    Full Text Available Recent work has indicated that platelets, which are anucleate blood cells, significantly contribute to inflammatory disorders. Importantly, platelets also likely contribute to various inflammatory secondary disorders that are increasingly associated with Human Immunodeficiency Virus Type-1 (HIV infection including neurological impairments and cardiovascular complications. Indeed, HIV infection is often associated with increased levels of platelet activators. Additionally, cocaine, a drug commonly abused by HIV-infected individuals, leads to increased platelet activation in humans. Considering that orchestrated signaling mechanisms are essential for platelet activation, and that nuclear factor-kappa B (NF-κB inhibitors can alter platelet function, the role of NF-κB signaling in platelet activation during HIV infection warrants further investigation. Here we tested the hypothesis that inhibitory kappa B kinase complex (IKK activation would be central for platelet activation induced by HIV and cocaine. Whole blood from HIV-positive and HIV-negative individuals, with or without cocaine abuse was used to assess platelet activation via flow cytometry whereas IKK activation was analyzed by performing immunoblotting and in vitro kinase assays. We demonstrate that increased platelet activation in HIV patients, as measured by CD62P expression, is not altered with reported cocaine use. Furthermore, cocaine and HIV do not activate platelets in whole blood when treated ex vivo. Finally, HIV-induced platelet activation does not involve the NF-κB signaling intermediate, IKKβ. Platelet activation in HIV patients is not altered with cocaine abuse. These results support the notion that non-IKK targeting approaches will be better suited for the treatment of HIV-associated inflammatory disorders.

  19. Human platelet glycoprotein Ia. One component is only expressed on the surface of activated platelets and may be a granule constituent

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    Bienz, D.; Clemetson, K.J.

    1989-01-05

    Glycoprotein Ia (GP Ia) is a relatively minor component of human blood platelets thought to be a receptor involved in collagen-induced platelet activation. However, some difficulties exist with the definition of this glycoprotein. The expression of GP Ia on resting (prostacyclin analogue-treated) and thrombin-activated platelets was compared by surface labeling with /sup 125/I-lactoperoxidase. Intact platelets or platelets solubilized in sodium dodecyl sulfate were labeled with periodate/(/sup 3/H)NaBH/sub 4/. Analysis on two-dimensional isoelectric focusing/sodium dodecyl sulfate-polyacrylamide gel electrophoresis gels showed that GP Ia is very poorly labeled in resting platelets. After activation a new spot (GP Ia*) appears with the same relative molecular mass as GP Ia under reducing conditions. GP Ia and Ia* can be clearly separated by two-dimensional nonreduced/reduced gel electrophoresis. Therefore, two glycoproteins which have been termed GP Ia exist in platelets with similar molecular weight and pI under reducing conditions. One of these (GP Ia*) is only surface-labeled when platelets are activated, indicating that it is only exposed on the surface of activated platelets. Supernatant from activated platelets contains this glycoprotein as well as other granule components. This glycoprotein is missing in platelets from two patients with collagen-response defects.

  20. Helicobacter pylori urease activates blood platelets through a lipoxygenase-mediated pathway.

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    Wassermann, German E; Olivera-Severo, Deiber; Uberti, Augusto F; Carlini, Célia R

    2010-07-01

    The bacterium Helicobacter pylori causes peptic ulcers and gastric cancer in human beings by mechanisms yet not fully understood. H. pylori produces urease which neutralizes the acidic medium permitting its survival in the stomach. We have previously shown that ureases from jackbean, soybean or Bacillus pasteurii induce blood platelet aggregation independently of their enzyme activity by a pathway requiring platelet secretion, activation of calcium channels and lipoxygenase-derived eicosanoids. We investigated whether H. pylori urease displays platelet-activating properties and defined biochemical pathways involved in this phenomenon. For that the effects of purified recombinant H. pylori urease (HPU) added to rabbit platelets were assessed turbidimetrically. ATP secretion and production of lipoxygenase metabolites by activated platelets were measured. Fluorescein-labelled HPU bound to platelets but not to erythrocytes. HPU induced aggregation of rabbit platelets (ED(50) 0.28 microM) accompanied by ATP secretion. No correlation was found between platelet activation and ureolytic activity of HPU. Platelet aggregation was blocked by esculetin (12-lipoxygenase inhibitor) and enhanced approximately 3-fold by indomethacin (cyclooxygenase inhibitor). A metabolite of 12-lipoxygenase was produced by platelets exposed to HPU. Platelet responses to HPU did not involve platelet-activating factor, but required activation of verapamil-inhibitable calcium channels. Our data show that purified H. pylori urease activates blood platelets at submicromolar concentrations. This property seems to be common to ureases regardless of their source (plant or bacteria) or quaternary structure (single, di- or tri-chain proteins). These properties of HPU could play an important role in pathogenesis of gastrointestinal and associated cardiovascular diseases caused by H. pylori.

  1. An inhibition of p38 mitogen activated protein kinase delays the platelet storage lesion.

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    Andrey Skripchenko

    Full Text Available BACKGROUND AND OBJECTIVES: Platelets during storage undergo diverse alterations collectively known as the platelet storage lesion, including metabolic, morphological, functional and structural changes. Some changes correlate with activation of p38 mitogen activated protein kinase (p38 MAPK. Another MAPK, extracellular signal-related kinase (ERK, is involved in PLT activation. The aim of this study was to compare the properties of platelets stored in plasma in the presence or absence of p38 and ERK MAPK inhibitors. MATERIALS AND METHODS: A single Trima apheresis platelet unit (n = 12 was aliquoted into five CLX storage bags. Two aliquots were continuously agitated with or without MAPK inhibitors. Two aliquots were subjected to 48 hours of interruption of agitation with or without MAPK inhibitors. One aliquot contained the same amount of solvent vehicle used to deliver the inhibitor. Platelets were stored at 20-24°C for 7 days and sampled on Days 1, 4, and 7 for 18 in vitro parameters. RESULTS: Inhibition of p38 MAPK by VX-702 leads to better maintenance of all platelet in vitro storage parameters including platelet mitochondrial function. Accelerated by interruption of agitation, the platelet storage lesion of units stored with VX-702 was diminished to that of platelets stored with continuous agitation. Inhibition of ERK MAPK did not ameliorate decrements in any in vitro platelet properties. CONCLUSION: Signaling through p38 MAPK, but not ERK, is associated with platelet deterioration during storage.

  2. SDF-1α is a novel autocrine activator of platelets operating through its receptor CXCR4.

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    Walsh, Tony G; Harper, Matthew T; Poole, Alastair W

    2015-01-01

    Platelets store and secrete the chemokine stromal cell-derived factor (SDF)-1α upon platelet activation, but the ability of platelet-derived SDF-1α to signal in an autocrine/paracrine manner mediating functional platelet responses relevant to thrombosis and haemostasis is unknown. We sought to explore the role of platelet-derived SDF-1α and its receptors, CXCR4 and CXCR7 in facilitating platelet activation and determine the mechanism facilitating SDF-1α-mediated regulation of platelet function. Using human washed platelets, CXCR4 inhibition, but not CXCR7 blockade significantly abrogated collagen-mediated platelet aggregation, dense granule secretion and thromboxane (Tx) A2 production. Time-dependent release of SDF-1α from collagen-activated platelets supports a functional role for SDF-1α in this regard. Using an in vitro whole blood perfusion assay, collagen-induced thrombus formation was substantially reduced with CXCR4 inhibition. In washed platelets, recombinant SDF-1α in the range of 20-100 ng/mL(-1) could significantly enhance platelet aggregation responses to a threshold concentration of collagen. These enhancements were completely dependent on CXCR4, but not CXCR7, which triggered TxA2 production and dense granule secretion. Rises in cAMP were significantly blunted by SDF-1α, which could also enhance collagen-mediated Ca2+ mobilisation, both of which were mediated by CXCR4. This potentiating effect of SDF-1α primarily required TxA2 signalling acting upstream of dense granule secretion, whereas blockade of ADP signalling could only partially attenuate SDF-1α-induced platelet activation. Therefore, this study supports a potentially novel autocrine/paracrine role for platelet-derived SDF-1α during thrombosis and haemostasis, through a predominantly TxA2-dependent and ADP-independent pathway.

  3. The activity of antioxidant enzymes in blood platelets in different types of renal replacement therapy: a cross-sectional study.

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    Stępniewska, Joanna; Dołęgowska, Barbara; Cecerska-Heryć, Elżbieta; Gołembiewska, Edyta; Malinowska-Jędraszczyk, Alicja; Marchelek-Myśliwiec, Małgorzata; Ciechanowski, Kazimierz

    2016-04-01

    The changes in redox status characterise physiological platelet activation. Increased oxidative stress in chronic kidney disease (CKD) associated with uremic toxicity and procedures of renal replacement therapy leads to the impairment of antioxidant properties of platelets. It may contribute to thrombosis and cardiovascular complications increasing morbidity and mortality among the CKD patients. The object of the research was to assess the influence of conservative treatment, peritoneal dialysis and haemodialysis on platelet prooxidative-antioxidative balance. The examined group consisted of 122 patients: 37 on regular haemodialysis (HD), 23 on peritoneal dialysis (PD) and 62 on conservative treatment with CKD stages 3-5 (CKD3-5). The activities of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPX), glutathione transpherase (GST) in platelets were obtained using kinetic methods. The spectrophotometric method established the concentrations of reduced glutathione (GSH). SOD activity in PD differs significantly from CKD3-5 (4.96 vs 1.66; p activity assessed in PD and CKD3-5 was significantly different from HD (0.82 and 0.8 vs 0.52 before and 0.35 after HD, respectively). GST activity reached the highest value in PD (1.62), and it was significantly different from CKD3-5 (0.23) and HD before haemodialysis (0.11). During haemodialysis therapy, there was a considerable increase in GST activity (0.11 vs 0.3; p = 0.02) and decrease in SOD activity (from 3.41 to 2.27; p = 0.01). The highest GSH concentrations were obtained in CKD3-5 and differ significantly from HD (4.12 vs 2.01; p = 0.02). The type of treatment, age and duration of renal replacement therapy determined significant changes in platelet antioxidative enzymes activities and concentration of GSH, which may enhance the thrombotic complications. PD is associated with lower platelet oxidative stress.

  4. Glatiramer acetate (copaxone modulates platelet activation and inhibits thrombin-induced calcium influx: possible role of copaxone in targeting platelets during autoimmune neuroinflammation.

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    Sarah C Starossom

    Full Text Available BACKGROUND: Glatiramer acetate (GA, Copaxone, Copolymer-1 is an FDA approved drug for the treatment of MS and it is very effective in suppressing neuroinflammation in experimental autoimmune encephalitis (EAE, an animal model of MS. Although this drug was designed to inhibit pathogenic T cells, the exact mechanism of EAE/MS suppression by GA is still not well understood. Previously we presented evidence that platelets become activated and promote neuroinflammation in EAE, suggesting a possible pathogenic role of platelets in MS and EAE. We hypothesized that GA could inhibit neuroinflammation by affecting not only immune cells but also platelets. METHODOLOGY/PRINCIPAL FINDINGS: We investigated the effect of GA on the activation of human platelets in vitro: calcium influx, platelet aggregation and expression of activation markers. Our results in human platelets were confirmed by in-vitro and in-vivo studies of modulation of functions of platelets in mouse model. We found that GA inhibited thrombin-induced calcium influx in human and mouse platelets. GA also decreased thrombin-induced CD31, CD62P, CD63, and active form of αIIbβ3 integrin surface expression and formation of platelet aggregates for both mouse and human platelets, and prolonged the bleeding time in mice by 2.7-fold. In addition, we found that GA decreased the extent of macrophage activation induced by co-culture of macrophages with platelets. CONCLUSIONS: GA inhibited the activation of platelets, which suggests a new mechanism of GA action in suppression of EAE/MS by targeting platelets and possibly preventing their interaction with immune cells such as macrophages. Furthermore, the reduction in platelet activation by GA may have additional cardiovascular benefits to prevent thrombosis.

  5. Platelet-rich fibrin (PRF): a second-generation platelet concentrate. Part III: leucocyte activation: a new feature for platelet concentrates?

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    Dohan, David M; Choukroun, Joseph; Diss, Antoine; Dohan, Steve L; Dohan, Anthony J J; Mouhyi, Jaafar; Gogly, Bruno

    2006-03-01

    Platelet-rich fibrin (PRF) belongs to a new generation of platelet concentrates, with simplified processing and without biochemical blood handling. In this third article, we investigate the immune features of this biomaterial. During PRF processing, leucocytes could also secrete cytokines in reaction to the hemostatic and inflammatory phenomena artificially induced in the centrifuged tube. We therefore undertook to quantify 5 significant cell mediators within platelet poor plasma supernatant and PRF clot exudate serum: 3 proinflammatory cytokines (IL-1beta, IL-6, and TNF-alpha), an antiinflammatory cytokine (IL-4), and a key growth promoter of angiogenesis (VEGF). Our data are correlated with that obtained in plasma (nonactivated blood) and in sera (activated blood). These initial analyses revealed that PRF could be an immune regulation node with inflammation retrocontrol abilities. This concept could explain the reduction of postoperative infections when PRF is used as surgical additive.

  6. HMGB1 binds to activated platelets via the receptor for advanced glycation end products and is present in platelet rich human coronary artery thrombi.

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    Ahrens, Ingo; Chen, Yung-Chih; Topcic, Danijal; Bode, Michael; Haenel, David; Hagemeyer, Christoph E; Seeba, Hannah; Duerschmied, Daniel; Bassler, Nicole; Jandeleit-Dahm, Karin A; Sweet, Matthew J; Agrotis, Alex; Bobik, Alex; Peter, Karlheinz

    2015-11-01

    High mobility group box 1 (HMGB1) acts as both a nuclear protein that regulates gene expression, as well as a pro-inflammatory alarmin that is released from necrotic or activated cells. Recently, HMGB1-expression in human atherosclerotic plaques was identified. Therapeutic blockade of HMGB1 reduced the development of diet-induced atherosclerosis in ApoE knockout mice. Thus, we hypothesised an interaction between HMGB1 and activated platelets. Binding of recombinant HMGB1 to platelets was assessed by flow cytometry. HMGB1 bound to thrombin-activated human platelets (MFI 2.49 vs 25.01, p=0.0079). Blood from wild-type, TLR4 and RAGE knockout mice was used to determine potential HMGB1 receptors on platelets. HMGB1 bound to platelets from wild type C57Bl6 (MFI 2.64 vs 20.3, p 0.05). RAGE expression on human platelets was detected by RT-PCR with mRNA extracted from highly purified platelets and confirmed by Western blot and immunofluorescence microscopy. Platelet activation increased RAGE surface expression (MFI 4.85 vs 6.74, p< 0.05). Expression of HMGB1 in human coronary artery thrombi was demonstrated by immunohistochemistry and revealed high expression levels. Platelets bind HMGB1 upon thrombin-induced activation. Platelet specific expression of RAGE could be detected at the mRNA and protein level and is involved in the binding of HMGB1. Furthermore, platelet activation up-regulates platelet surface expression of RAGE. HMGB1 is highly expressed in platelet-rich human coronary artery thrombi pointing towards a central role for HMGB1 in atherothrombosis, thereby suggesting the possibility of platelet targeted anti-inflammatory therapies for atherothrombosis.

  7. Platelet activation using electric pulse stimulation: growth factor profile and clinical implications.

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    Torres, Andrew S; Caiafa, Antonio; Garner, Allen L; Klopman, Steve; LaPlante, Nicole; Morton, Christine; Conway, Kenneth; Michelson, Alan D; Frelinger, Andrew L; Neculaes, V Bogdan

    2014-09-01

    Autologous platelet gel therapy using platelet-rich plasma has emerged as a promising alternative for chronic wound healing, hemostasis, and wound infection control. A critical step for this therapeutic approach is platelet activation, typically performed using bovine thrombin (BT) and calcium chloride. However, exposure of humans to BT can stimulate antibody formation, potentially resulting in severe hemorrhagic or thrombotic complications. Electric pulse stimulation using nanosecond PEFs (pulse electric fields) is an alternative, nonbiochemical platelet activation method, thereby avoiding exposure to xenogeneic thrombin and associated risks. In this study, we identified specific requirements for a clinically relevant activator instrument by dynamically measuring current, voltage, and electric impedance for platelet-rich plasma samples. From these samples, we investigated the profile of growth factors released from human platelets with electric pulse stimulation versus BT, specifically platelet-derived growth factor, transforming growth factor β, and epidermal growth factor, using commercial enzyme-linked immunosorbent assay kits. Electric pulse stimulation triggers growth factor release from platelet α-granules at the same or higher level compared with BT. Electric pulse stimulation is a fast, inexpensive, easy-to-use platelet activation method for autologous platelet gel therapy.

  8. Platelet-activating factor in cirrhotic liver and hepatocellular carcinoma

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    Muriel Mathonnet; Bernard Descottes; Denis Valleix; Véronique Truffinet; Francois Labrousse; Yves Denizot

    2006-01-01

    AIM: Platelet-activating factor (PAF) is a pro-inflammatory and angiogenic lipid mediator. Here we aimed to investigate levels of PAF, lyso-PAF (the PAF precursor),phospholipase A2 (PLA2, the enzymatic activity generating lyso-PAF), acetylhydrolase activity (AHA, the PAF degrading enzyme) and PAF receptor (PAF-R) transcripts in cirrhotic liver and hepatocellular carcinoma (HCC).METHODS: Twenty-nine patients with HCC were ehrolled in this study. Cirrhosis was present in fourteen patients and seven had no liver disease. Tissue PAF levels were investigated by a platelet-aggregation assay. LysoPAF was assessed after its chemical acetylation into PAF.AHA was determined by degradation of [3H]-PAF. PLA2 levels were assessed by EIA. PAF-R transcripts were investigated using RT-PCR.RESULTS: Elevated amounts of PAF and PAF-R transcripts 1 (leukocyte-type) were found in cirrhotic tissues as compared with non-cirrhotic ones. Higher amounts of PAF and PAF-R transcripts 1 and 2 (tissue-type) were found in HCC tissues as compared with non-tumor tissues. PLA2, lyso-PAF and AHA levels were not changed in cirrhotic tissues and HCC.CONCLUSION: While the role of PAF is currently unknown in liver physiology, this study suggests its potential involvement in the inflammatory network found in the cirrhotic liver and in the angiogenic response during HCC.

  9. Inhibitory effect of GBH on platelet aggregation through inhibition of intracellular Ca2+ mobilization in activated human platelets.

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    Park, Won-Hwan; Kim, Han-Kyu; Nam, Kyung-Soo; Shon, Yun-Hee; Jeon, Byung Hun; Moon, Sung-Kwon; Kim, Min-Gon; Kim, Cheorl-Ho

    2004-11-05

    Geiji-Bokryung-Hwan (GBH) was studied on antiplatelet activity in human platelet suspensions. GBH consists of the 5 herbs Cinnamomi Ramulus, Poria Cocos, Mountan Cortex Radicis, Paeoniae Radix, and Persicae Semen, which have been used in herbal medicine for thousands of years for atherosclerosis. The mechanism involved in the antiplatelet activity of GBH in human platelet suspensions was investigated. GBH inhibited platelet aggregation and Ca2+ mobilization in a concentration-dependent manner without increasing intracellular cyclic AMP and cyclic GMP. GBH had no inhibitory effect on thromboxane B2 (TXB2) production in cell-free systems. Collagen-related peptide (CRP)-induced Ca2+ mobilization is regulated by phospholipase C-2 (PLC-gamma2) activation. We evaluated the effect of GBH on tyrosine phosphorylation of PLC-gamma2 and the production of inositol-1,4,5-trisphosphate (IP3). GBH at concentrations that inhibited platelet aggregation and Ca2+ mobilization had no effects on tyrosine phosphorylation of PLC-gamma2 or on the formation of IP3 induced by CRP. Similar results were obtained with thrombin-induced platelet activation. GBH inhibited platelet aggregation and Ca2+ mobilization induced by thrombin without affecting the production of IP3. We then evaluated the effect of GBH on the binding of IP3 to its receptor. GBH at high concentrations partially blocked the binding of IP3 to its receptor. Therefore, the results suggested that GBH suppresses Ca2+ mobilization at a step distal to IP3 formation. GBH may provide a good tool for investigating Ca2+ mobilization.

  10. Correlation between Platelet Gelsolin and Platelet Activation Level in Acute Myocardial Infarction Rats and Intervention Effect of Effective Components of Chuanxiong Rhizome and Red Peony Root

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    Yue Liu

    2013-01-01

    Full Text Available The biological role of platelet gelsolin in platelet activation of acute myocardial infarction is not defined. In order to provide a potential new antiplatelet target for Chinese medicine and to elucidate the contribution of Xiongshao capsule, the effective components of Chuanxiong rhizome and red peony root, in this study, we randomly allocated Sprague Dawley rats to left anterior descending coronary artery ligation or sham surgery and different drug prophylaxis as control. We found that gelsolin is highly expressed in platelet rich plasma and lowly expressed in platelet poor plasma, accompanied by the high platelet activation level in model rats; plasma actin filaments and mean fluorescence intensity (MFI of platelet calcium ion increased and plasma vitamin D binding protein decreased in model rats. Xiongshao capsule could inhibit the gelsolin expression in platelet rich plasma and ischemic heart tissue simultaneously and reduce the level of plasma F-actin and MFI of platelet calcium ion. Our study concludes that platelet gelsolin is an important contributor to platelet activation, and platelet gelsolin inhibition may form a novel target for antiplatelet therapy. Xiongshao capsule may be a promising Chinese medicine drug for antiplatelet and aspirin-like cardioprotection effect.

  11. Actively induced platelet-bound IgG associated with thrombocytopenia in the marmoset

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    Gengozian, N.; McLaughlin, C.L.

    1978-06-01

    Interspecies platelet immunizations among marmosets lead to antibody formation to the donor platelets and a profound thrombocytopenia, which when associated with anemia may result in death of the animal. This actively induced immonologic thrombocytopenia closely resembles two clinical disease entities manifesting autoimmune thrombocytopenia, posttransfusion purpura and idiopathic thrombocytopenic purpura. Although antibody to donor-type platelets could be demonstrated readily, antihost activity was most often nondetectable or, when present, was in very low titer. A consistent finding was the appearance of IgG on the host's platelets shortly after immunization and concomitant with the appearance of antidonor platelet antibody. In 3 of 13 immunized animals thromoocytopenia did not occur even though antibody was formed and the host's platelets became IgG positive. In those animals that recovered from the induced thrombocytopenia IgG-positive platelets were found for periods ranging from 30 to greater than 100 days. Splenectomy before or after immunization did not alter the sequential development of antibody formation, appearance of IgG-positive platelets, and thrombocytopenia. Eluates prepared from IgG-positive platelets contained IgG and platelet antigens; the eluted IgG could attach nonspecifically to platelets of host or donor (immunizing) type, in contrast to the species specificity demonstrated for IgG eluted from platelets that had been reacted in vitro with specific antibody. Platelets in a few normal, nonimmunized marmosets were found to have signficant amounts of IgG on their surface, comparable to that observed in the immunized animal; interestingly, such IgG-positive platelets were found among imported but not laboratory-bred marmosets.

  12. Activation of circulating platelets and platelet response to activating agents in children with cyanotic congenital heart disease: their relevance to palliative systemic-pulmonary shunt.

    Science.gov (United States)

    Kierzkowska, B; Stańczyk, J; Wiectawska, B; Rózalski, M; Boncler, M; Chrul, S; Watala, C

    2001-06-01

    Abnormal platelet function has been hypothesised to play a role in the haemostatic abnormalities in cyanotic congenital heart disease (CCHD) patients. Using whole blood flow cytometry we found that platelets from cyanotic patients were hyperreactive and we related such hyperreactivity directly to young age, unoperated state, high haematocrit, reduced saturation with oxygen and low platelet count. Circulating platelets from CCHD children showed significantly enhanced P-selectin expression (Pplatelet 'priming' largely concerned CCHD children who were not subjected to modified Blalock-Taussig shunts in the past (non-MBTS). Only non-MBTS cyanotic children, but not MBTS-operated patients, showed significantly higher platelet reactivity compared to controls in response to ADP or 1 microM TRAP with respect to P-selectin expression (pchildren and reduced GPIb expression in non-MBTS patients, especially in younger patients, were positively associated with the occurrence of the polymorphic variant Pl(A2) of platelet membrane glycoprotein IIIa gene. Altered blood morphology parameters (elevated RBC, Hb, Hct and MCHC, for all Pchildren correlated with the enhanced degranulation of circulating blood platelets and their hyperreactivity in response to some agonists (Pplatelets are remarkably hyperreactive in non-MBTS cyanotic children, which are at higher risk to often encounter platelets activation in circulation. It seems unlikely that the apparently unchanged platelet reactivity in MBTS-operated children is due to the advantageous effects of the shunt, since these patients showed neither altered haematological parameters nor improved oxygen carrying capacity. Otherwise, it may rather result from more frequent episodes of platelet degranulation and preactivation in the past, and/or post-operative enhanced platelet consumption.

  13. Cigarette smoking inhibits the anti-platelet activity of aspirin in patients with coronary heart disease

    Institute of Scientific and Technical Information of China (English)

    LI Wei-ju; ZHANG Hong-yin; MIAO Cheng-long; TANG Ri-bo; DU Xin; SHI Ji-hui; MA Chang-sheng

    2011-01-01

    Objective Tobacco smoking results in increased platelet aggregability, which suggests that low-dose aspirin used in common clinical practice may not effectively inhibit platelet activity in smokers with coronary heart disease (CHD). This review was performed to assess the effect of aspirin on platelet aggregation in patients with CHD.Data sources We performed an electronic literature search of MEDLINE (starting from the beginning to March 15, 2009)using the term "smoking" or "tobacco" paired with the following: "platelet", "aspirin" or "coronary heart disease".Study selection We looked for review articles regarding the effect of tobacco smoking on platelet activity and on the anti-platelet efficacy of aspirin in healthy people and patients with CHD. The search was limited in "core clinical journal".In total, 1321 relevant articles were retrieved, and 36 articles were ultimately cited.Results Tobacco smoking results in increased platelet aggregability, which can be inhibited by low-dose aspirin in the healthy population. However, in patients with CHD, the increased platelet aggregability can not be effectively inhibited by the same low-dose of aspirin. A recent study indicated that clopidogrel or an increased dose of aspirin can effectively inhibit the increased platelet aggregability induced by tobacco smoking in patients with CHD.Conclusions It is important for patients with CHD to quit smoking. For the current smoker, it may be necessary to take larger doses of aspirin than normal or take an adenosine diphosphate receptor inhibitor along with aspirin to effectively inhibit the increased platelet activity.

  14. Platelets mediate increased endothelium permeability in dengue through NLRP3-inflammasome activation.

    Science.gov (United States)

    Hottz, Eugenio D; Lopes, Juliana F; Freitas, Carla; Valls-de-Souza, Rogério; Oliveira, Marcus F; Bozza, Marcelo T; Da Poian, Andrea T; Weyrich, Andrew S; Zimmerman, Guy A; Bozza, Fernando A; Bozza, Patricia T

    2013-11-14

    Dengue is the most frequent hemorrhagic viral disease and re-emergent infection in the world. Although thrombocytopenia is characteristically observed in mild and severe forms of dengue, the role of platelet activation in dengue pathogenesis has not been fully elucidated. We hypothesize that platelets have major roles in inflammatory amplification and increased vascular permeability during severe forms of dengue. Here we investigate interleukin (IL)-1β synthesis, processing, and secretion in platelets during dengue virus (DV) infection and potential contribution of these events to endothelial permeability during infection. We observed increased expression of IL-1β in platelets and platelet-derived microparticles from patients with dengue or after platelet exposure to DV in vitro. We demonstrated that DV infection leads to assembly of nucleotide-binding domain leucine rich repeat containing protein (NLRP3) inflammasomes, activation of caspase-1, and caspase-1-dependent IL-1β secretion. Our findings also indicate that platelet-derived IL-1β is chiefly released in microparticles through mechanisms dependent on mitochondrial reactive oxygen species-triggered NLRP3 inflammasomes. Inflammasome activation and platelet shedding of IL-1β-rich microparticles correlated with signs of increased vascular permeability. Moreover, microparticles from DV-stimulated platelets induced enhanced permeability in vitro in an IL-1-dependent manner. Our findings provide new evidence that platelets contribute to increased vascular permeability in DV infection by inflammasome-dependent release of IL-1β.

  15. Effect of montelukast on platelet activating factor- and tachykinin induced mucus secretion in the rat

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    Groneberg David A

    2008-02-01

    Full Text Available Abstract Background Platelet activating factor and tachykinins (substance P, neurokinin A, neurokinin B are important mediators contributing to increased airway secretion in the context of different types of respiratory diseases including acute and chronic asthma. Leukotriene receptor antagonists are recommended as add-on therapy for this disease. The cys-leukotriene-1 receptor antagonist montelukast has been used in clinical asthma therapy during the last years. Besides its inhibitory action on bronchoconstriction, only little is known about its effects on airway secretions. Therefore, the aim of this study was to evaluate the effects of montelukast on platelet activating factor- and tachykinin induced tracheal secretory activity. Methods The effects of montelukast on platelet activating factor- and tachykinin induced tracheal secretory activity in the rat were assessed by quantification of secreted 35SO4 labelled mucus macromolecules using the modified Ussing chamber technique. Results Platelet activating factor potently stimulated airway secretion, which was completely inhibited by the platelet activating factor receptor antagonist WEB 2086 and montelukast. In contrast, montelukast had no effect on tachykinin induced tracheal secretory activity. Conclusion Cys-leukotriene-1 receptor antagonism by montelukast reverses the secretagogue properties of platelet activating factor to the same degree as the specific platelet activating factor antagonist WEB 2086 but has no influence on treacheal secretion elicited by tachykinins. These results suggest a role of montelukast in the signal transduction pathway of platelet activating factor induced secretory activity of the airways and may further explain the beneficial properties of cys-leukotriene-1 receptor antagonists.

  16. Characterization of the platelet-aggregating activity of cancer cells with different metastatic potential.

    Science.gov (United States)

    Grignani, G; Pacchiarini, L; Almasio, P; Pagliarino, M; Gamba, G; Rizzo, S C; Ascari, E

    1986-08-15

    We studied the mechanisms of platelet activation by sublines exhibiting different metastatic potential of two murine experimental tumors: sublines M4 and M9 of the benzopyrene-induced mFS6 sarcoma and sublines B77-AA6 and B77-3T3 of RSV-transformed BALB/c 3T3 fibroblasts. The neoplastic cells of both models induced platelet aggregation, secretion and prostaglandin biosynthesis. In the first model but not in the second, all these processes correlated with the in vivo malignancy of cells. Pretreatment of B77-AA6 and B77-3T3 cells with apyrase significantly decreased platelet aggregation, while pretreatment of M4 cells was ineffective. However, pretreatment with trypsin or neuraminidase was effective in reducing platelet aggregation induced by M4 cells, but not that induced by any of the others; furthermore, phospholipase A2 reduced the platelet response by all sublines. Finally, platelet-activating activity was also found in the pellets obtained following centrifugation of culture media. These results suggest that platelets are stimulated by cancer cells through different mechanisms; platelet activation by a sialo-lipo-protein complex of the cellular membrane was found to be characteristic of the model in which the platelet-aggregating activity of neoplastic cells correlated with their in vivo metastatic behavior.

  17. PGE2 decreases reactivity of human platelets by activating EP2 and EP4.

    Science.gov (United States)

    Smith, James P; Haddad, Elias V; Downey, Jason D; Breyer, Richard M; Boutaud, Olivier

    2010-07-01

    Platelet hyperreactivity associates with cardiovascular events in humans. Studies in mice and humans suggest that prostaglandin E2 (PGE2) regulates platelet activation. In mice, activation of the PGE2 receptor subtype 3 (EP3) promotes thrombosis, but the significance of EP3 in humans is less well understood. To characterize the regulation of thromboxane-dependent human platelet activation by PGE2. Platelets collected from nineteen healthy adults were studied using an agonist of the thromboxane receptor (U46,619), PGE2, and selective agonists and/or antagonists of the EP receptor subtypes. Platelet activation was assayed by (1) optical aggregometry, (2) measurement of dense granule release, and (3) single-platelet counting. Healthy volunteers demonstrated significant interindividual variation in platelet response to PGE2. PGE2 completely inhibited U46,619-induced platelet aggregation and ATP release in 26% of subjects; the remaining 74% had partial or no response to PGE2. Antagonism of EP4 abolished the inhibitory effect of PGE2. In all volunteers, a selective EP2 agonist inhibited U46,619-induced aggregation. Furthermore, the selective EP3 antagonist DG-041 converted all PGE2 nonresponders to full responders. There is significant interindividual variation of platelet response to PGE2 in humans. The balance between EP2, EP3, and EP4 activation determines its net effect. PGE2 can prevent thromboxane-induced platelet aggregation in an EP4-dependent manner. EP3 antagonism converts platelets of nonresponders to a PGE2-responsive phenotype. These data suggest that therapeutic targeting of EP pathways may have cardiovascular benefit by decreasing platelet reactivity. Copyright (c) 2010 Elsevier Ltd. All rights reserved.

  18. Echicetin coated polystyrene beads: a novel tool to investigate GPIb-specific platelet activation and aggregation.

    Directory of Open Access Journals (Sweden)

    Alexey Navdaev

    Full Text Available von Willebrand factor/ristocetin (vWF/R induces GPIb-dependent platelet agglutination and activation of αIIbβ3 integrin, which also binds vWF. These conditions make it difficult to investigate GPIb-specific signaling pathways in washed platelets. Here, we investigated the specific mechanisms of GPIb signaling using echicetin-coated polystyrene beads, which specifically activate GPIb. We compared platelet activation induced by echicetin beads to vWF/R. Human platelets were stimulated with polystyrene beads coated with increasing amounts of echicetin and platelet activation by echicetin beads was then investigated to reveal GPIb specific signaling. Echicetin beads induced αIIbβ3-dependent aggregation of washed platelets, while under the same conditions vWF/R treatment led only to αIIbβ3-independent platelet agglutination. The average distance between the echicetin molecules on the polystyrene beads must be less than 7 nm for full platelet activation, while the total amount of echicetin used for activation is not critical. Echicetin beads induced strong phosphorylation of several proteins including p38, ERK and PKB. Synergistic signaling via P2Y12 and thromboxane receptor through secreted ADP and TxA2, respectively, were important for echicetin bead triggered platelet activation. Activation of PKG by the NO/sGC/cGMP pathway inhibited echicetin bead-induced platelet aggregation. Echicetin-coated beads are powerful and reliable tools to study signaling in human platelets activated solely via GPIb and GPIb-triggered pathways.

  19. Echicetin Coated Polystyrene Beads: A Novel Tool to Investigate GPIb-Specific Platelet Activation and Aggregation

    Science.gov (United States)

    Petunin, Alexey; Clemetson, Kenneth J.; Gambaryan, Stepan; Walter, Ulrich

    2014-01-01

    von Willebrand factor/ristocetin (vWF/R) induces GPIb-dependent platelet agglutination and activation of αIIbβ3 integrin, which also binds vWF. These conditions make it difficult to investigate GPIb-specific signaling pathways in washed platelets. Here, we investigated the specific mechanisms of GPIb signaling using echicetin-coated polystyrene beads, which specifically activate GPIb. We compared platelet activation induced by echicetin beads to vWF/R. Human platelets were stimulated with polystyrene beads coated with increasing amounts of echicetin and platelet activation by echicetin beads was then investigated to reveal GPIb specific signaling. Echicetin beads induced αIIbβ3-dependent aggregation of washed platelets, while under the same conditions vWF/R treatment led only to αIIbβ3-independent platelet agglutination. The average distance between the echicetin molecules on the polystyrene beads must be less than 7 nm for full platelet activation, while the total amount of echicetin used for activation is not critical. Echicetin beads induced strong phosphorylation of several proteins including p38, ERK and PKB. Synergistic signaling via P2Y12 and thromboxane receptor through secreted ADP and TxA2, respectively, were important for echicetin bead triggered platelet activation. Activation of PKG by the NO/sGC/cGMP pathway inhibited echicetin bead-induced platelet aggregation. Echicetin-coated beads are powerful and reliable tools to study signaling in human platelets activated solely via GPIb and GPIb-triggered pathways. PMID:24705415

  20. Elevated plasma phospholipase A2 and platelet-activating factor acetylhydrolase activity in colorectal cancer

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    Yves Denizot

    2004-01-01

    Full Text Available This clinical study reports that blood levels of the pro-inflammatory mediator platelet-activating factor (PAF did not change in colorectal cancer patients. In contrast, plasma levels of two enzymatic activities, one implicated in PAF production (i.e. phospholipase A2 and one in PAF degradation (i.e. PAF acetylhydrolase activity were significantly elevated.

  1. Murine monoclonal antibody to platelet factor 4/heparin complexes as a potential reference standard for platelet activation assays in heparin-induced thrombocytopenia.

    Science.gov (United States)

    Asada, Reiko; Wanaka, Keiko; Walenga, Jeanine; Prechel, Margaret; Miyashita, Kumiko; Escalante, Vicki; Kaneko, Chieko; Hoshino, Nobuhiro; Oosawa, Mitsuru; Matsuo, Miyako

    2013-01-01

    Quality control of the platelet activation assays to diagnose heparin-induced thrombocytopenia (HIT), (14)C-serotonin release assay (SRA) and platelet aggregation test (PAT) has yet to be established due to lack of reference standards and the difficulty of obtaining significant amounts of HIT antibodies from patients with HIT. We prepared a murine monoclonal antibody to human platelet factor 4 (hPF4)/heparin complexes (HIT-MoAb) and investigated the platelet activating action of HIT-MoAb by using SRA and PAT. The HIT-MoAb activated human platelets at low heparin concentration and the platelet activations were inhibited at high heparin concentration in both SRA and PAT. The HIT-MoAb produced a concentration-dependent effect. Moreover, the platelet activation at low heparin concentration was inhibited by anti-FcγRIIa antibody. These results indicated that HIT-MoAb has characteristics similar to human HIT antibodies regarding heparin-dependent platelet activation. Therefore, it is suggested that HIT-MoAb has the potential to be a positive control or reference standard in platelet activation assays.

  2. A practical synthesis of sarpogrelate hydrochloride and in vitro platelet aggregation inhibitory activities of its analogues

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    A convenient approach for the preparation of sarpogrelate hydrochloride was developed.Two series of sarpogrelate hydrochloride analogues were designed and synthesized in order to improve their platelet aggregation inhibitory activities, biological tests suggested that these compounds have platelet aggregation inhibitory activities to some extent.

  3. Alterations in 32P-labelled intermediates during flux activation of human platelet glycolysis

    NARCIS (Netherlands)

    Akkerman, Jan Willem N.; Driver, H.A.; Dangelmaier, C.A.; Holmsen, H.

    1984-01-01

    Using a newly developed isotopic tracer technique for the measurement of 32P-labelled intermediates in glycolysis and nucleotide metabolism in platelets, we studied the variations in 32P-labelled intermediates during activation of the glycolytic flux by cyanide and platelet-activating agents. The ma

  4. Platelet function and activation in Cavalier King Charles Spaniels with subclinical chronic valvular heart disease.

    Science.gov (United States)

    Tong, Linda J; Hosgood, Giselle L; French, Anne T; Irwin, Peter J; Shiel, Robert E

    2016-08-01

    OBJECTIVE To assess platelet closure time (CT), mean platelet component (MPC) concentration, and platelet component distribution width (PCDW) in dogs with subclinical chronic valvular heart disease. ANIMALS 89 Cavalier King Charles Spaniels (CKCSs) and 39 control dogs (not CKCSs). PROCEDURES Platelet count, MPC concentration, PCDW, and Hct were measured by use of a hematology analyzer, and CT was measured by use of a platelet function analyzer. Murmur grade and echocardiographic variables (mitral valve regurgitant jet size relative to left atrial area, left atrial-to-aortic diameter ratio, and left ventricular internal dimensions) were recorded. Associations between explanatory variables (sex, age, murmur grade, echocardiographic variables, platelet count, and Hct) and outcomes (CT, MPC concentration, and PCDW) were examined by use of multivariate regression models. RESULTS A model with 5 variables best explained variation in CT (R(2), 0.74), with > 60% of the variance of CT explained by mitral valve regurgitant jet size. The model of best fit to explain variation in MPC concentration included only platelet count (R(2), 0.24). The model of best fit to explain variation in PCDW included platelet count and sex (R(2), 0.25). CONCLUSIONS AND CLINICAL RELEVANCE In this study, a significant effect of mitral valve regurgitant jet size on CT was consistent with platelet dysfunction. However, platelet activation, as assessed on the basis of the MPC concentration and PCDW, was not a feature of subclinical chronic valvular heart disease in CKCSs.

  5. The NLRP3 inflammasome and bruton's tyrosine kinase in platelets co-regulate platelet activation, aggregation, and in vitro thrombus formation.

    Science.gov (United States)

    Murthy, Pranav; Durco, Filip; Miller-Ocuin, Jennifer L; Takedai, Teiko; Shankar, Shruthi; Liang, Xiaoyan; Liu, Xiao; Cui, Xiangdong; Sachdev, Ulka; Rath, Dominik; Lotze, Michael T; Zeh, Herbert J; Gawaz, Meinrad; Weber, Alexander N; Vogel, Sebastian

    2017-01-29

    Cleavage of interleukin-1β (IL-1β) is a key inflammatory event in immune cells and platelets, which is mediated by nucleotide-binding domain leucine rich repeat containing protein (NLRP3)-dependent activation of caspase-1. In immune cells, NLRP3 and caspase-1 form inflammasome complexes with the adaptor proteins apoptosis-associated speck-like protein containing a CARD (ASC) and bruton's tyrosine kinase (BTK). In platelets, however, the regulatory triggers and the functional effects of the NLRP3 inflammasome are unknown. Here, we show in vitro that the platelet NLRP3 inflammasome contributes to platelet activation, aggregation, and thrombus formation. NLRP3 activity, as monitored by caspase-1 activation and cleavage and secretion of IL-1β, was upregulated in activated platelets, which was dependent on platelet BTK. Pharmacological inhibition or genetic ablation of BTK in platelets led to decreased platelet activation, aggregation, and in vitro thrombus formation. We identify a functionally relevant link between BTK and NLRP3 in platelets, with potential implications in disease states associated with abnormal coagulation and inflammation. Copyright © 2016 Elsevier Inc. All rights reserved.

  6. The effects of residual platelets in plasma on plasminogen activator inhibitor-1 and plasminogen activator inhibitor-1-related assays

    Science.gov (United States)

    Barnard, Sunelle A.; Loots, Du Toit; Rijken, Dingeman C.

    2017-01-01

    Due to controversial evidence in the literature pertaining to the activity of plasminogen activator inhibitor-1 in platelets, we examined the effects of residual platelets present in plasma (a potential pre-analytical variable) on various plasminogen activator inhibitor-1 and plasminogen activator inhibitor-1-related assays. Blood samples were collected from 151 individuals and centrifuged at 352 and 1500 g to obtain plasma with varying numbers of platelet. In a follow-up study, blood samples were collected from an additional 23 individuals, from whom platelet-poor (2000 g), platelet-containing (352 g) and platelet-rich plasma (200 g) were prepared and analysed as fresh-frozen and after five defrost-refreeze cycles (to determine the contribution of in vitro platelet degradation). Plasminogen activator inhibitor-1 activity, plasminogen activator inhibitor-1 antigen, tissue plasminogen activator/plasminogen activator inhibitor-1 complex, plasma clot lysis time, β-thromboglobulin and plasma platelet count were analysed. Platelet α-granule release (plasma β-thromboglobulin) showed a significant association with plasminogen activator inhibitor-1 antigen levels but weak associations with plasminogen activator inhibitor-1 activity and a functional marker of fibrinolysis, clot lysis time. Upon dividing the study population into quartiles based on β-thromboglobulin levels, plasminogen activator inhibitor-1 antigen increased significantly across the quartiles while plasminogen activator inhibitor-1 activity and clot lysis time tended to increase in the 4th quartile only. In the follow-up study, plasma plasminogen activator inhibitor-1 antigen was also significantly influenced by platelet count in a concentration-dependent manner. Plasma plasminogen activator inhibitor-1 antigen levels increased further after complete platelet degradation. Residual platelets in plasma significantly influence plasma plasminogen activator inhibitor-1 antigen levels mainly through release of

  7. Complement Component C3 Binds to Activated Normal Platelets without Preceding Proteolytic Activation and Promotes Binding to Complement Receptor 1

    NARCIS (Netherlands)

    O.A. Hamad; P.H. Nilsson; D. Wouters; J.D. Lambris; K.N. Ekdahl; B. Nilsson

    2010-01-01

    It has been reported that complement is activated on the surface of activated platelets, despite the presence of multiple regulators of complement activation. To reinvestigate the mechanisms by which activated platelets bind to complement components, the presence of complement proteins on the surfac

  8. Amarogentin, a Secoiridoid Glycoside, Abrogates Platelet Activation through PLCγ2-PKC and MAPK Pathways

    Directory of Open Access Journals (Sweden)

    Ting-Lin Yen

    2014-01-01

    Full Text Available Amarogentin, an active principle of Gentiana lutea, possess antitumorigenic, antidiabetic, and antioxidative properties. Activation of platelets is associated with intravascular thrombosis and cardiovascular diseases. The present study examined the effects of amarogentin on platelet activation. Amarogentin treatment (15~60 μM inhibited platelet aggregation induced by collagen, but not thrombin, arachidonic acid, and U46619. Amarogentin inhibited collagen-induced phosphorylation of phospholipase C (PLCγ2, protein kinase C (PKC, and mitogen-activated protein kinases (MAPKs. It also inhibits in vivo thrombus formation in mice. In addition, neither the guanylate cyclase inhibitor ODQ nor the adenylate cyclase inhibitor SQ22536 affected the amarogentin-mediated inhibition of platelet aggregation, which suggests that amarogentin does not regulate the levels of cyclic AMP and cyclic GMP. In conclusion, amarogentin prevents platelet activation through the inhibition of PLCγ2-PKC cascade and MAPK pathway. Our findings suggest that amarogentin may offer therapeutic potential for preventing or treating thromboembolic disorders.

  9. Platelets Express Activated P2Y12 Receptor in Patients With Diabetes Mellitus.

    Science.gov (United States)

    Hu, Liang; Chang, Lin; Zhang, Yan; Zhai, Lili; Zhang, Shenghui; Qi, Zhiyong; Yan, Hongmei; Yan, Yan; Luo, Xinping; Zhang, Si; Wang, Yiping; Kunapuli, Satya P; Ye, Hongying; Ding, Zhongren

    2017-08-29

    Platelets from patients with diabetes mellitus are hyperactive. Hyperactivated platelets may contribute to cardiovascular complications and inadequate responses to antiplatelet agents in the setting of diabetes mellitus. However, the underlying mechanism of hyperactivated platelets is not completely understood. We measured P2Y12 expression on platelets from patients with type 2 diabetes mellitus and on platelets from rats with diabetes mellitus. We also assayed platelet P2Y12 activation by measuring cAMP and VASP phosphorylation. The antiplatelet and antithrombotic effects of AR-C78511 and cangrelor were compared in rats. Finally, we explored the role of the nuclear factor-κB pathway in regulating P2Y12 receptor expression in megakaryocytes. Platelet P2Y12 levels are 4-fold higher in patients with type 2 diabetes mellitus compared with healthy subjects. P2Y12 expression correlates with ADP-induced platelet aggregation (r=0.89, Pdiabetes mellitus is constitutively activated. Although both AR-C78511, a potent P2Y12 inverse agonist, and cangrelor have similar antiplatelet efficacy on platelets from healthy subjects, AR-C78511 exhibits more powerful antiplatelet effects on diabetic platelets than cangrelor (aggregation ratio 36±3% versus 49±5%, respectively, Pdiabetes mellitus than cangrelor (thrombus weight 4.9±0.3 mg versus 8.3±0.4 mg, respectively, Pdiabetes mellitus. Platelet P2Y12 receptor expression is significantly increased and the receptor is constitutively activated in patients with type 2 diabetes mellitus, which contributes to platelet hyperactivity and limits antiplatelet drug efficacy in type 2 diabetes mellitus. © 2017 American Heart Association, Inc.

  10. Activated platelets release sphingosine 1-phosphate and induce hypersensitivity to noxious heat stimuli in vivo

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    Daniela eWeth

    2015-04-01

    Full Text Available At the site of injury activated platelets release various mediators, one of which is sphingosine 1-phosphate (S1P. It was the aim of this study to explore whether activated human platelets had a pronociceptive effect in an in vivo mouse model and whether this effect was based on the release of S1P and subsequent activation of neuronal S1P receptors 1 or 3. Human platelets were prepared in different concentrations (105/µl, 106/µl, 107/µl and assessed in mice with different genetic backgrounds (WT, S1P1fl/fl, SNS-S1P1-/-, S1P3-/-. Intracutaneous injections of activated human platelets induced a significant, dose-dependent hypersensitivity to noxious thermal stimulation. The degree of heat hypersensitivity correlated with the platelet concentration as well as the platelet S1P content and the amount of S1P released upon platelet activation as measured with LC MS/MS. Despite the significant correlations between S1P and platelet count, no difference in paw withdrawal latency (PWL was observed in mice with a global null mutation of the S1P3 receptor or a conditional deletion of the S1P1 receptor in nociceptive primary afferents. Furthermore, neutralisation of S1P with a selective anti-S1P antibody did not abolish platelet induced heat hypersensitivity. Our results suggest that activated platelets release S1P and induce heat hypersensitivity in vivo. However, the platelet induced heat hypersensitivity was caused by mediators other than S1P.

  11. The influence of statin therapy on platelet activity markers in hyperlipidemic patients after ischemic stroke

    Science.gov (United States)

    Chmielewski, Henryk; Kaczorowska, Beata; Przybyła, Monika; Baj, Zbigniew

    2015-01-01

    Introduction Low-density lipoprotein cholesterol (LDL-C) has been reported to increase platelet activation. Reducing the level of LDL-C with statins induces important pleiotropic effects such as platelet inhibition. This association between platelet activity and statin therapy may be clinically important in reducing the risk of ischemic stroke. We investigated the effect of simvastatin therapy on platelet activation markers (platelet CD62P, sP-selectin, and platelet-derived microparticles (PDMPs)) in hyperlipidemic patients after ischemic stroke. Material and methods The study group consisted of 21 hyperlipidemic patients after ischemic stroke confirmed by CT, and 20 healthy subjects served as controls. We assessed the CD62P expression on resting and thrombin-activated blood platelets. CD62P and PDMPs were analyzed by the use of monoclonal antibodies anti-CD61 and anti-CD62 on a flow cytometer. The level of sP-selectin in serum was measured by the ELISA (enzyme-linked immunosorbent assay) method. All markers were re-analyzed after 6 months of treatment with simvastatin (20 mg/day). Results Hyperlipidemic patients presented a significantly higher percentage of CD62+ platelets and higher reactivity to thrombin compared to control subjects. After simvastatin therapy hyperlipidemic patients showed a reduction of the percentage of resting CD62P(+) platelets (p = 0.005) and a reduction of expression and percentage of CD62P(+) platelets after activation by thrombin (median p < 0.05; percentage: p = 0.001). A decrease of sP-selectin levels (p = 0.001) and percentage of PDMPs (p < 0.05) in this group was also observed. Conclusions HMG-CoA reductase inhibitor therapy in stroke patients with hyperlipidemia may be useful not only due to the lipid-lowering effect but also because of a significant role in reduction of platelet activation and reactivity. PMID:25861297

  12. VAMP-7 links granule exocytosis to actin reorganization during platelet activation.

    Science.gov (United States)

    Koseoglu, Secil; Peters, Christian G; Fitch-Tewfik, Jennifer L; Aisiku, Omozuanvbo; Danglot, Lydia; Galli, Thierry; Flaumenhaft, Robert

    2015-07-30

    Platelet activation results in profound morphologic changes accompanied by release of granule contents. Recent evidence indicates that fusion of granules with the plasma membrane during activation provides auxiliary membrane to cover growing actin structures. Yet little is known about how membrane fusion is coupled with actin reorganization. Vesicle-associated membrane protein (VAMP)-7 is found on platelet vesicles and possesses an N-terminal longin domain capable of linking exocytosis to cytoskeletal remodeling. We have evaluated platelets from VAMP-7(-/-) mice to determine whether this VAMP isoform contributes to granule release and platelet spreading. VAMP-7(-/-) platelets demonstrated a partial defect in dense granule exocytosis and impaired aggregation. α Granule exocytosis from VAMP-7(-/-) platelets was diminished both in vitro and in vivo during thrombus formation. Consistent with a role of VAMP-7 in cytoskeletal remodeling, spreading on matrices was decreased in VAMP-7(-/-) platelets compared to wild-type controls. Immunoprecipitation of VAMP-7 revealed an association with VPS9-domain ankyrin repeat protein (VARP), an adaptor protein that interacts with both membrane-bound and cytoskeleton proteins and with Arp2/3. VAMP-7, VARP, and Arp2/3 localized to the platelet periphery during spreading. These studies demonstrate that VAMP-7 participates in both platelet granule secretion and spreading and suggest a mechanism whereby VAMP-7 links granule exocytosis with actin reorganization.

  13. Accurate measurement of volume and shape of resting and activated blood platelets from light scattering

    Science.gov (United States)

    Moskalensky, Alexander E.; Yurkin, Maxim A.; Konokhova, Anastasiya I.; Strokotov, Dmitry I.; Nekrasov, Vyacheslav M.; Chernyshev, Andrei V.; Tsvetovskaya, Galina A.; Chikova, Elena D.; Maltsev, Valeri P.

    2013-01-01

    We introduce a novel approach for determination of volume and shape of individual blood platelets modeled as an oblate spheroid from angle-resolved light scattering with flow-cytometric technique. The light-scattering profiles (LSPs) of individual platelets were measured with the scanning flow cytometer and the platelet characteristics were determined from the solution of the inverse light-scattering problem using the precomputed database of theoretical LSPs. We revealed a phenomenon of parameter compensation, which is partly explained in the framework of anomalous diffraction approximation. To overcome this problem, additional a priori information on the platelet refractive index was used. It allowed us to determine the size of each platelet with subdiffraction precision and independent of the particular value of the platelet aspect ratio. The shape (spheroidal aspect ratio) distributions of platelets showed substantial differences between native and activated by 10 μM adenosine diphosphate samples. We expect that the new approach may find use in hematological analyzers for accurate measurement of platelet volume distribution and for determination of the platelet activation efficiency.

  14. Accurate measurement of volume and shape of resting and activated blood platelets from light scattering.

    Science.gov (United States)

    Moskalensky, Alexander E; Yurkin, Maxim A; Konokhova, Anastasiya I; Strokotov, Dmitry I; Nekrasov, Vyacheslav M; Chernyshev, Andrei V; Tsvetovskaya, Galina A; Chikova, Elena D; Maltsev, Valeri P

    2013-01-01

    We introduce a novel approach for determination of volume and shape of individual blood platelets modeled as an oblate spheroid from angle-resolved light scattering with flow-cytometric technique. The light-scattering profiles (LSPs) of individual platelets were measured with the scanning flow cytometer and the platelet characteristics were determined from the solution of the inverse light-scattering problem using the precomputed database of theoretical LSPs. We revealed a phenomenon of parameter compensation, which is partly explained in the framework of anomalous diffraction approximation. To overcome this problem, additional a priori information on the platelet refractive index was used. It allowed us to determine the size of each platelet with subdiffraction precision and independent of the particular value of the platelet aspect ratio. The shape (spheroidal aspect ratio) distributions of platelets showed substantial differences between native and activated by 10 μM adenosine diphosphate samples. We expect that the new approach may find use in hematological analyzers for accurate measurement of platelet volume distribution and for determination of the platelet activation efficiency.

  15. Clearance of circulating activated platelets in polycythemia vera and essential thrombocythemia.

    Science.gov (United States)

    Maugeri, Norma; Malato, Simona; Femia, Eti A; Pugliano, Mariateresa; Campana, Lara; Lunghi, Francesca; Rovere-Querini, Patrizia; Lussana, Federico; Podda, Gianmarco; Cattaneo, Marco; Ciceri, Fabio; Manfredi, Angelo A

    2011-09-22

    Essential thrombocythemia (ET) and polycythemia vera (PV) are characterized by persistent platelet activation. The mechanisms involved in their clearance are poorly characterized. In the present study, we report that leukocytes were actively involved in platelet disposal in 51 patients with ET and 30 with PV, but not in 70 age- and sex-matched controls. The fraction of circulating neutrophils and monocytes that had phagocytosed platelets, as assessed by flow cytometry, was significantly higher in patients with PV or ET, independently of hydroxyurea treatment, than in controls. Platelet phagocytosis by circulating leukocytes was confirmed by confocal and electron microscopy. The lack of effect of hydroxyurea, which disrupts the P-selectin/P-selectin glycoprotein ligand 1 (PSGL-1) interaction, suggests a P-selectin-independent mechanism. This hypothesis was confirmed in an ad hoc animal model based on the in vivo injection of activated platelets from P-selectin(+/+) and P-selectin(-/-) mice. P-selectin expression was associated with an earlier and effective clearance of platelets by neutrophils. A second delayed, P-selectin-independent phase actively involved monocytes. Our results suggest that phagocytic clearance of platelets by leukocytes occurs in PV and ET, possibly involving P-selectin-dependent and -independent pathways, thus representing a novel mechanism to remove activated platelets from the circulation.

  16. Effect of red blood cells on platelet activation and thrombus formation in tortuous arterioles

    Directory of Open Access Journals (Sweden)

    Jennifer K. W. Chesnutt

    2013-12-01

    Full Text Available Thrombosis is a major contributor to cardiovascular disease, which can lead to myocardial infarction and stroke. Thrombosis may form in tortuous microvessels, which are often seen throughout the human body, but the microscale mechanisms and processes are not well understood. In straight vessels, the presence of red blood cells (RBCs is known to push platelets toward walls, which may affect platelet aggregation and thrombus formation. However in tortuous vessels, the effects of RBC interactions with platelets in thrombosis are largely unknown. Accordingly, the objective of this work was to determine the physical effects of RBCs, platelet size, and vessel tortuosity on platelet activation and thrombus formation in tortuous arterioles. A discrete element computational model was used to simulate the transport, collision, adhesion, aggregation, and shear-induced platelet activation of hundreds of individual platelets and RBCs in thrombus formation in tortuous arterioles. Results showed that high shear stress near the inner sides of curved arteriole walls activated platelets to initiate thrombosis. RBCs initially promoted platelet activation, but then collisions of RBCs with mural thrombi reduced the amount of mural thrombus and the size of emboli. In the absence of RBCs, mural thrombus mass was smaller in a highly tortuous arteriole compared to a less tortuous arteriole. In the presence of RBCs however, mural thrombus mass was larger in the highly tortuous arteriole compared to the less tortuous arteriole. As well, smaller platelet size yielded less mural thrombus mass and smaller emboli, either with or without RBCs. This study shed light on microscopic interactions of RBCs and platelets in tortuous microvessels, which have implications in various pathologies associated with thrombosis and bleeding.

  17. Effect of Red Blood Cells on Platelet Activation and Thrombus Formation in Tortuous Arterioles.

    Science.gov (United States)

    Chesnutt, Jennifer K W; Han, Hai-Chao

    2013-01-01

    Thrombosis is a major contributor to cardiovascular disease, which can lead to myocardial infarction and stroke. Thrombosis may form in tortuous microvessels, which are often seen throughout the human body, but the microscale mechanisms and processes are not well understood. In straight vessels, the presence of red blood cells (RBCs) is known to push platelets toward walls, which may affect platelet aggregation and thrombus formation. However in tortuous vessels, the effects of RBC interactions with platelets in thrombosis are largely unknown. Accordingly, the objective of this work was to determine the physical effects of RBCs, platelet size, and vessel tortuosity on platelet activation and thrombus formation in tortuous arterioles. A discrete element computational model was used to simulate the transport, collision, adhesion, aggregation, and shear-induced platelet activation of hundreds of individual platelets and RBCs in thrombus formation in tortuous arterioles. Results showed that high shear stress near the inner sides of curved arteriole walls activated platelets to initiate thrombosis. RBCs initially promoted platelet activation, but then collisions of RBCs with mural thrombi reduced the amount of mural thrombus and the size of emboli. In the absence of RBCs, mural thrombus mass was smaller in a highly tortuous arteriole compared to a less tortuous arteriole. In the presence of RBCs however, mural thrombus mass was larger in the highly tortuous arteriole compared to the less tortuous arteriole. As well, smaller platelet size yielded less mural thrombus mass and smaller emboli, either with or without RBCs. This study shed light on microscopic interactions of RBCs and platelets in tortuous microvessels, which have implications in various pathologies associated with thrombosis and bleeding.

  18. Platelet microbicidal activity is an important defense factor against viridans streptococcal endocarditis

    NARCIS (Netherlands)

    Krijgsveld, J; Joldersma, W; Zaat, SAJ; van der Werff, J.

    2001-01-01

    To study the role of platelet microbicidal activity in host defense against infective endocarditis (IE) due to viridans streptococci (VS), the susceptibility to platelet releasate of blood and oral VS isolates from patients with and without IE was compared. The influence of neutralization of platele

  19. Prostaglandin A1 inhibits increases in intracellular calcium concentration, TXA2 production and platelet activation

    Institute of Scientific and Technical Information of China (English)

    Yi ZHU; Zhen-lun GU; Zhong-qin LIANG; Hui-lin ZHANG; Zheng-hong QIN

    2006-01-01

    Aim: In our previous studies we found that cyclopentenane prostaglandin A1 (PGA1) had neuroprotective effects in a rodent ischemic model. In the present study we aimed to investigate the inhibitory effect of PGA1 on platelet function. Method: The rate of aggregation of human platelets was measured by using turbidimetry. The rate of adhesion of platelets to cultured endothelial cells was determined by using [3H]-adenine labeled platelets. 5-Hydroxytryptamine release from platelets was measured with O-phthaldialdehyde fluorospectrophotometry. The levels of TXB2, a stable metabolite of TXA2, were determined by radioimmunoassay. Alternations in platelet morphology were observed using an electron microscope, and the intraplatelet free calcium concentrations were measured with Fluo-3/AM FCM assay. Results: PGA1 significantly inhibited thrombin-collagen-and ADP-induced aggregation and adhesion of platelets. The morphological changes of platelets induced by thrombin were blocked by PGA1. PGA1 inhibited the release of 5-hydroxytyptamine from dense granules and the synthesis of TXA2. Conclusion: PGA1 inhibits the activation of platelets probably through blocking increases in intracellular calcium concentration and TXA2 synthesis.

  20. Duration of exposure to high fluid shear stress is critical in shear-induced platelet activation-aggregation.

    Science.gov (United States)

    Zhang, Jian-ning; Bergeron, Angela L; Yu, Qinghua; Sun, Carol; McBride, Latresha; Bray, Paul F; Dong, Jing-fei

    2003-10-01

    Platelet functions are increasingly measured under flow conditions to account for blood hydrodynamic effects. Typically, these studies involve exposing platelets to high shear stress for periods significantly longer than would occur in vivo. In the current study, we demonstrate that the platelet response to high shear depends on the duration of shear exposure. In response to a 100 dyn/cm2 shear stress for periods less than 10-20 sec, platelets in PRP or washed platelets were aggregated, but minimally activated as demonstrated by P-selectin expression and binding of the activation-dependent alphaIIbbeta3 antibody PAC-1 to sheared platelets. Furthermore, platelet aggregation under such short pulses of high shear was subjected to rapid disaggregation. The disaggregated platelets could be re-aggregated by ADP in a pattern similar to unsheared platelets. In comparison, platelets that are exposed to high shear for longer than 20 sec are activated and aggregated irreversibly. In contrast, platelet activation and aggregation were significantly greater in whole blood with significantly less disaggregation. The enhancement is likely via increased collision frequency of platelet-platelet interaction and duration of platelet-platelet association due to high cell density. It may also be attributed to the ADP release from other cells such as red blood cells because increased platelet aggregation in whole blood was partially inhibited by ADP blockage. These studies demonstrate that platelets have a higher threshold for shear stress than previously believed. In a pathologically relevant timeframe, high shear alone is likely to be insufficient in inducing platelet activation and aggregation, but acts synergistically with other stimuli.

  1. Systemic platelet dysfunction is the result of local dysregulated coagulation and platelet activation in the brain in a rat model of isolated traumatic brain injury.

    Science.gov (United States)

    Ploplis, Victoria A; Donahue, Deborah L; Sandoval-Cooper, Mayra J; MorenoCaffaro, Maria; Sheets, Patrick; Thomas, Scott G; Walsh, Mark; Castellino, Francis J

    2014-10-01

    Coagulopathy after severe traumatic brain injury (TBI) has been extensively reported. Clinical studies have identified a strong relationship between diminished platelet-rich thrombus formation, responsiveness to adenosine diphosphate agonism, and severity of TBI. The mechanisms that lead to platelet dysfunction in the acute response to TBI are poorly understood. The development of a rodent model of TBI that mimics the coagulopathy observed clinically has recently been reported. Using immunohistochemical techniques and thromboelastography platelet mapping, the current study demonstrated that the expression of coagulation (tissue factor and fibrin) and platelet activation (P-selectin) markers in the injured brain paralleled the alteration in systemic platelet responsiveness to the agonists, adenosine diphosphate and arachodonic acid. Results of this study demonstrate that local procoagulant changes in the injured brain have profound effects on systemic platelet function.

  2. Blood platelet and monocyte activations and relation to stages of liver cirrhosis

    Institute of Scientific and Technical Information of China (English)

    Anatol Panasiuk; Janusz Zak; Edwina Kasprzycka; Katarzyna Janicka; Danuta Prokopowicz

    2005-01-01

    AIM: Blood platelets (plt) and monocytes are the cells that play a crucial role in the pathogenesis of liver damage and liver cirrhosis (LC). In this paper, the analysis of mutual relationship between platelets and monocytes activation in LC was conducted.METHODS: Immunofluorescent flow cytometry was usedto measure the percentage of activated platelet populations(CD62P, CD63), the percentage of plt-monocyte aggregates (pma) (CD41/CD45), and activated monocytes (CD11b, CD14, CD16) in the blood of 20 volunteers and 40 patientswith LC. Platelet activation markers: sP-selectin, platelet factor 4 (PF4), beta-thromboglobulin (βTG) and monocyte chemotactic peptide-1 (MCP-1) were measured and compared in different stages of LC.RESULTS: Platelet activation with the increase in bothβTG serum concentration and elevation of plt population(CD62P and CD63 as well as MIF CD62P and CD63) is elevated as LC develops and thrombocytopenia rises. There is a positive correlation between medial intensityof fluorescence (MIF) CD62P and MIF CD63 in LC. We did not show any relationship between monocyte activation and pma level. SP-selectin concentration correlates positively with plt count and pma, and negatively with stage of plt activation and MIF CD62P and MIF CD63. There was no correlation between MCP-1 concentration andpit, monocyte activation as well as pma level in LC. CD16 monocytes and MIF CD16 populations are significantlyhigher in the end stage of LC. A positive correlation occurs between the value of CD11b monocyte population andMIF CD14 and MIF CD16 on monocytes in LC.CONCLUSION: Platelet and monocyte activation plays an important role in LC. Platelet activation stage does not influence monocyte activation and production of plt aggregates with monocytes in LC. With LC development, thrombocytopenia may be the result of plt consumption in platelet-monocyte aggregates.

  3. Rac1 is essential for phospholipase C-gamma2 activation in platelets

    DEFF Research Database (Denmark)

    Pleines, Irina; Elvers, Margitta; Strehl, Amrei

    2008-01-01

    Platelet activation at sites of vascular injury is triggered through different signaling pathways leading to activation of phospholipase (PL) Cbeta or PLCgamma2. Active PLCs trigger Ca(2+) mobilization and entry, which is a prerequisite for adhesion, secretion, and thrombus formation. PLCbeta...... isoenzymes are activated downstream of G protein-coupled receptors (GPCRs), whereas PLCgamma2 is activated downstream of immunoreceptor tyrosine-based activation motif (ITAM)-coupled receptors, such as the major platelet collagen receptor glycoprotein (GP) VI or CLEC-2. The mechanisms underlying PLC...... regulation are not fully understood. An involvement of small GTPases of the Rho family (Rho, Rac, Cdc42) in PLC activation has been proposed but this has not been investigated in platelets. We here show that murine platelets lacking Rac1 display severely impaired GPVI- or CLEC-2-dependent activation...

  4. Fractions of aqueous and methanolic extracts from tomato (Solanum lycopersicum L.) present platelet antiaggregant activity.

    Science.gov (United States)

    Fuentes, Eduado J; Astudillo, Luis A; Gutiérrez, Margarita I; Contreras, Samuel O; Bustamante, Luis O; Rubio, Pia I; Moore-Carrasco, Rodrigo; Alarcón, Marcelo A; Fuentes, Jaime A; González, Daniel E; Palomo, Iván F

    2012-03-01

    Cardiovascular disease (CVD) is the leading cause of death worldwide. Its prevention emphasizes three aspects: not smoking, physical activity and a healthy diet. Recently, we screened the antithrombotic activity of a selected group of fruits and vegetables. Among them, tomato showed an important effect. The aim of this study was to evaluate and characterize the platelet antiaggregatory activity of tomato (Solanum lycopersicum L.). For this, we obtained aqueous and methanolic tomato extracts and evaluated the effect of pH (2 and 10) and temperature (22, 60 and 100°C) on this activity. Furthermore, in order to isolate the antiaggregant principle, we separated tomato extracts into several fractions (A-D) by size exclusion chromatography. In addition, we evaluated the platelet antiaggregating activity ex vivo in Wistar rats. Aqueous and methanolic extracts of tomato treated at 22, 60 and 100°C and pH 2 and 10 still inhibited platelet aggregation (in vitro). Moreover, it was noted that one of the fractions (fraction C), from both aqueous and methanolic extracts, presented the highest activity (∼70% inhibition of platelet aggregation) and concentration dependently inhibited platelet aggregation significantly compared with control (P lycopene but presented two peaks of absorption, at 210 and 261 nm, compatible with the presence of nucleosides. In rats treated with tomato macerates, a mild platelet antiaggregating effect ex vivo was observed. Further studies are required to identify the molecules with platelet antiaggregating activity and antiplatelet mechanisms of action.

  5. Platelet-activating factor (PAF) receptor-binding antagonist activity of Malaysian medicinal plants.

    Science.gov (United States)

    Jantan, I; Rafi, I A A; Jalil, J

    2005-01-01

    Forty-nine methanol extracts of 37 species of Malaysian medicinal plants were investigated for their inhibitory effects on platelet-activating factor (PAF) binding to rabbit platelets, using 3H-PAF as a ligand. Among them, the extracts of six Zingiberaceae species (Alpinia galanga Swartz., Boesenbergia pandurata Roxb., Curcuma ochorrhiza Val., C. aeruginosa Roxb., Zingiber officinale Rosc. and Z. zerumbet Koenig.), two Cinnamomum species (C. altissimum Kosterm. and C. pubescens Kochummen.), Goniothalamus malayanus Hook. f. Momordica charantia Linn. and Piper aduncum L. are potential sources of new PAF antagonists, as they showed significant inhibitory effects with IC50 values ranging from 1.2 to 18.4 microg ml(-1).

  6. Antimicrobial/anti-biofilm activity of expired blood platelets and their released products 

    Directory of Open Access Journals (Sweden)

    Marcin I. Różalski

    2013-04-01

    Full Text Available Introduction. Although platelets are not part of the classical immune system, they have many features that indicate their role in the anti-infective host defense. They come into interactions with microorganisms, which results in co-aggregation and co-adhesion or destruction of themicrobes due to the action of antimicrobial peptides released from platelets.The aim of this study was to evaluate the killing effect of platelets against planktonic and biofilm cultures of Staphylococcus aureus and to test their synergy with antibiotics. Materials and Methods. S. aureus ATCC 29213; platelet rich plasma (1-3 days post shelf life. Evaluation of bactericidal activity of platelets or their lysates against planktonic cultures of S. aureus – CFU calculation after 4- and 24-hour co-incubation. Assessment of S. aureus biofilm viability under the influence of platelets – Live/Dead® BacLightTM Bacterial Viability Kit. Determination of minimum inhibitory concentrations (MICs (oxacillin, vancomycin, linezolid and estimation of the synergistic action of antibiotics and platelet lysates – a gradient-diffusion test strip. Results. Microbicidal activity of “expired” platelets and their lysates has been shown as a significant reduction in the population of staphylococci in their planktonic cultures by 56-87�0and a decrease in metabolic activity of biofilm formation by 7-38�20These activities were enhanced after activation with ADP. Platelet lysates showed a synergistic effect with β-lactam antibiotic (oxacillin and glycopeptide (vancomycin but not with oxazolidinone (linezolid. Conclusions and Discussion. In summary, platelets even after the medical expiry date are still a good source of antimicrobial low molecular weight proteins (PMPs. Testing of bacterialresistance to PMPs may be advisable as a predictive indicator of susceptibility to treatment of infections such as infective endocarditis and other local infections of biofilm nature.

  7. The nitric oxide donor pentaerythritol tetranitrate reduces platelet activation in congestive heart failure.

    Directory of Open Access Journals (Sweden)

    Ulrike Flierl

    Full Text Available Platelet activation associated with endothelial dysfunction and impaired endogenous platelet inhibition is part of the cardiovascular phenotype of congestive heart failure (CHF and contributes to the increased risk for thromboembolic complications. Pentaerythritol tetranitrate (PETN has been shown to release nitric oxide without development of nitrate tolerance. We investigated the effect of chronic PETN treatment on platelet activation and aggregation in an experimental CHF model.Chronic ischemic heart failure was induced in male Wistar rats by coronary artery ligation. Starting 7 days thereafter, rats were randomised to placebo or PETN (80 mg/kg twice daily. After 9 weeks, activation of circulating platelets was determined measuring platelet bound fibrinogen, which requires activated glycoprotein IIb/IIIa on the platelet surface. Binding was quantified by flow-cytometry using a FITC-labelled anti-fibrinogen antibody. Platelet-bound fibrinogen was significantly increased in CHF-Placebo (mean fluorescence intensity: Sham 88±4, CHF-Placebo 104±6, p<0.05 and reduced following treatment with PETN (89±7, p<0.05 vs. CHF-Placebo. Maximal and final ADP-induced aggregation was significantly enhanced in CHF-Placebo vs. Sham-operated animals and normalized / decreased following chronic PETN treatment. Moreover, platelet adhesion was significantly reduced (number of adherent platelets: control: 85.6±5.5, PETN: 40±3.3; p<0.001 and VASP phosphorylation significantly enhanced following in vitro PETN treatment.Chronic NO supplementation using PETN reduces platelet activation in CHF rats. Thus, PETN may constitute a useful approach to prevent thromboembolic complications in CHF.

  8. Glaucocalyxin A inhibits platelet activation and thrombus formation preferentially via GPVI signaling pathway.

    Directory of Open Access Journals (Sweden)

    Wei Li

    Full Text Available Platelets play a pivotal role in atherothrombosis and the antiplatelet agents have been proved to be useful in preventing onset of acute clinical events including myocardial infarction and stroke. Increasing number of natural compounds has been identified to be potential antiplatelet agents. Here we report the antiplatelet effect of glaucocalyxin A (GLA, an ent-diterpenoid that we isolated and purified from the aerial parts of Rabdosia japonica (Burm. f. var. glaucocalyx (Maxim. Hara, and investigate the molecular mechanisms by which GLA inhibits platelet activation and thrombus formation. The effect of GLA on platelet activation was measured using platelets freshly isolated from peripheral blood of healthy donors. Results showed that pretreatment of human platelets with lower concentrations of GLA (0.01 μg/ml, 0.1 μg/ml significantly inhibited platelet aggregation induced by collagen (P<0.001 and CRP (P<0.01, a synthetic GPVI ligand, but not by ADP and U46619. Accordingly, GLA inhibited collagen-stimulated tyrosine phosphorylation of Syk, LAT, and phospholipase Cγ2, the signaling events in collagen receptor GPⅥ pathway. GLA also inhibited platelet p-selectin secretion and integrin activation by convulxin, a GPVI selective ligand. Additionally, GLA was found to inhibit low-dose thrombin-induced platelet activation. Using a flow chamber device, GLA was found to attenuate platelet adhesion on collagen surfaces in high shear condition. In vivo studies showed that GLA administration increased the time for complete occlusion upon vascular injury in mice, but did not extend tail-bleeding time when mice were administered with relatively lower doses of GLA. Therefore, the present results provide the molecular basis for the inhibition effect of GLA on platelet activation and its in vivo effect on thrombus formation, suggesting that GLA could potentially be developed as an antiplatelet and antithrombotic agent.

  9. Thrombopoietin potentiates agonist-stimulated activation of p38 mitogen-activated protein kinase in human platelets.

    Science.gov (United States)

    Ezumi, Y; Nishida, E; Uchiyama, T; Takayama, H

    1999-07-22

    Thrombopoietin (TPO) plays a crucial role in megakaryocyte differentiation and platelet production. c-Mpl, a receptor for TPO, is also expressed in terminally differentiated platelets. We investigated the effects of TPO on activation of p38 mitogen-activated protein kinase in human platelets. Thrombin, a thrombin receptor agonist peptide, a thromboxane A(2) analogue, collagen, crosslinking the glycoprotein VI, ADP, and epinephrine, but not phorbol 12, 13-dibutyrate activated p38. TPO did not activate p38 by itself, whereas TPO pretreatment potentiated the agonist-induced activation of p38. TPO did not promote phosphorylation of Hsp27 and cytosolic phospholipase A(2) by itself, but enhanced thrombin-induced phosphorylation of them. The specific p38 inhibitor SB203580 strongly inhibited such phosphorylation. Thus, TPO possesses the priming effect on p38 activation in human platelets and could affect platelet functions through the p38 pathway. Copyright 1999 Academic Press.

  10. Platelet factor 4 impairs the anticoagulant activity of activated protein C.

    LENUS (Irish Health Repository)

    Preston, Roger J S

    2009-02-27

    Platelet factor 4 (PF4) is an abundant platelet alpha-granule chemokine released following platelet activation. PF4 interacts with thrombomodulin and the gamma-carboxyglutamic acid (Gla) domain of protein C, thereby enhancing activated protein C (APC) generation by the thrombin-thrombomodulin complex. However, the protein C Gla domain not only mediates protein C activation in vivo, but also plays a critical role in modulating the diverse functional properties of APC once generated. In this study we demonstrate that PF4 significantly inhibits APC anti-coagulant activity. PF4 inhibited both protein S-dependent APC anticoagulant function in plasma and protein S-dependent factor Va (FVa) proteolysis 3- to 5-fold, demonstrating that PF4 impairs protein S cofactor enhancement of APC anticoagulant function. Using recombinant factor Va variants FVa-R506Q\\/R679Q and FVa-R306Q\\/R679Q, PF4 was shown to impair APC proteolysis of FVa at position Arg(306) by 3-fold both in the presence and absence of protein S. These data suggest that PF4 contributes to the poorly understood APC resistance phenotype associated with activated platelets. Finally, despite PF4 binding to the APC Gla domain, we show that APC in the presence of PF4 retains its ability to initiate PAR-1-mediated cytoprotective signaling. In summary, we propose that PF4 acts as a critical regulator of APC generation, but also differentially targets APC toward cytoprotective, rather than anticoagulant function at sites of vascular injury with concurrent platelet activation.

  11. Platelet factor 4 impairs the anticoagulant activity of activated protein C.

    LENUS (Irish Health Repository)

    Preston, Roger J S

    2012-02-01

    Platelet factor 4 (PF4) is an abundant platelet alpha-granule chemokine released following platelet activation. PF4 interacts with thrombomodulin and the gamma-carboxyglutamic acid (Gla) domain of protein C, thereby enhancing activated protein C (APC) generation by the thrombin-thrombomodulin complex. However, the protein C Gla domain not only mediates protein C activation in vivo, but also plays a critical role in modulating the diverse functional properties of APC once generated. In this study we demonstrate that PF4 significantly inhibits APC anti-coagulant activity. PF4 inhibited both protein S-dependent APC anticoagulant function in plasma and protein S-dependent factor Va (FVa) proteolysis 3- to 5-fold, demonstrating that PF4 impairs protein S cofactor enhancement of APC anticoagulant function. Using recombinant factor Va variants FVa-R506Q\\/R679Q and FVa-R306Q\\/R679Q, PF4 was shown to impair APC proteolysis of FVa at position Arg(306) by 3-fold both in the presence and absence of protein S. These data suggest that PF4 contributes to the poorly understood APC resistance phenotype associated with activated platelets. Finally, despite PF4 binding to the APC Gla domain, we show that APC in the presence of PF4 retains its ability to initiate PAR-1-mediated cytoprotective signaling. In summary, we propose that PF4 acts as a critical regulator of APC generation, but also differentially targets APC toward cytoprotective, rather than anticoagulant function at sites of vascular injury with concurrent platelet activation.

  12. Modification of Pulsed Electric Field Conditions Results in Distinct Activation Profiles of Platelet-Rich Plasma

    Science.gov (United States)

    Frelinger, Andrew L.; Gerrits, Anja J.; Garner, Allen L.; Torres, Andrew S.; Caiafa, Antonio; Morton, Christine A.; Berny-Lang, Michelle A.; Carmichael, Sabrina L.; Neculaes, V. Bogdan; Michelson, Alan D.

    2016-01-01

    Background Activated autologous platelet-rich plasma (PRP) used in therapeutic wound healing applications is poorly characterized and standardized. Using pulsed electric fields (PEF) to activate platelets may reduce variability and eliminate complications associated with the use of bovine thrombin. We previously reported that exposing PRP to sub-microsecond duration, high electric field (SMHEF) pulses generates a greater number of platelet-derived microparticles, increased expression of prothrombotic platelet surfaces, and differential release of growth factors compared to thrombin. Moreover, the platelet releasate produced by SMHEF pulses induced greater cell proliferation than plasma. Aims To determine whether sub-microsecond duration, low electric field (SMLEF) bipolar pulses results in differential activation of PRP compared to SMHEF, with respect to profiles of activation markers, growth factor release, and cell proliferation capacity. Methods PRP activation by SMLEF bipolar pulses was compared to SMHEF pulses and bovine thrombin. PRP was prepared using the Harvest SmartPreP2 System from acid citrate dextrose anticoagulated healthy donor blood. PEF activation by either SMHEF or SMLEF pulses was performed using a standard electroporation cuvette preloaded with CaCl2 and a prototype instrument designed to take into account the electrical properties of PRP. Flow cytometry was used to assess platelet surface P-selectin expression, and annexin V binding. Platelet-derived growth factor (PDGF), vascular endothelial growth factor (VEGF), endothelial growth factor (EGF) and platelet factor 4 (PF4), and were measured by ELISA. The ability of supernatants to stimulate proliferation of human epithelial cells in culture was also evaluated. Controls included vehicle-treated, unactivated PRP and PRP with 10 mM CaCl2 activated with 1 U/mL bovine thrombin. Results PRP activated with SMLEF bipolar pulses or thrombin had similar light scatter profiles, consistent with the

  13. Platelet-Activating Factor Induces Th17 Cell Differentiation

    Directory of Open Access Journals (Sweden)

    Anne-Marie Drolet

    2011-01-01

    Full Text Available Th17 cells have been implicated in a number of inflammatory and autoimmune diseases. The phospholipid mediator platelet-activating factor (PAF is found in increased concentrations in inflammatory lesions and has been shown to induce IL-6 production. We investigated whether PAF could affect the development of Th17 cells. Picomolar concentrations of PAF induced IL-23, IL-6, and IL-1β expression in monocyte-derived Langerhans cells (LCs and in keratinocytes. Moreover, when LC were pretreated with PAF and then cocultured with anti-CD3- and anti-CD28-activated T cells, the latter developed a Th17 phenotype, with a significant increase in the expression of the transcriptional regulator RORγt and enhanced expression of IL-17, IL-21, and IL-22. PAF-induced Th17 development was prevented by the PAF receptor antagonist WEB2086 and by neutralizing antibodies to IL-23 and IL-6R. This may constitute a previously unknown stimulus for the development and persistence of inflammatory processes that could be amenable to pharmacologic intervention.

  14. Platelet activation during exercise induced asthma: effect of prophylaxis with cromoglycate and salbutamol.

    Science.gov (United States)

    Johnson, C E; Belfield, P W; Davis, S; Cooke, N J; Spencer, A; Davies, J A

    1986-01-01

    Peak expiratory flow (PEF) and plasma concentrations of platelet factor 4 and beta thromboglobulin were measured before and after exercise in nine asthmatic patients and 12 non-asthmatic volunteers. Exercise was preceded by administration in random order of either placebo, salbutamol 200 micrograms, or sodium cromoglycate 2 mg from a pressurised inhaler. In control subjects there were minimal changes in PEF and plasma concentrations of platelet factor 4 and beta thromboglobulin. In the asthmatic patients the typical changes in PEF were seen on exercise; plasma concentrations of platelet factor 4 and beta thromboglobulin rose significantly in parallel, the rise preceding the fall in PEF. The changes in peak flow and platelet activation induced by exercise were attenuated by prior administration of salbutamol or cromoglycate. These results indicate that exercise induced asthma is associated with a rise in platelet release products similar to that observed in antigen induced asthma. PMID:2943049

  15. The tyrosine phosphatase CD148 is an essential positive regulator of platelet activation and thrombosis.

    Science.gov (United States)

    Senis, Yotis A; Tomlinson, Michael G; Ellison, Stuart; Mazharian, Alexandra; Lim, Jenson; Zhao, Yan; Kornerup, Kristin N; Auger, Jocelyn M; Thomas, Steve G; Dhanjal, Tarvinder; Kalia, Neena; Zhu, Jing W; Weiss, Arthur; Watson, Steve P

    2009-05-14

    Platelets play a fundamental role in hemostasis and thrombosis. They are also involved in pathologic conditions resulting from blocked blood vessels, including myocardial infarction and ischemic stroke. Platelet adhesion, activation, and aggregation at sites of vascular injury are regulated by a diverse repertoire of tyrosine kinase-linked and G protein-coupled receptors. Src family kinases (SFKs) play a central role in initiating and propagating signaling from several platelet surface receptors; however, the underlying mechanism of how SFK activity is regulated in platelets remains unclear. CD148 is the only receptor-like protein tyrosine phosphatase identified in platelets to date. In the present study, we show that mutant mice lacking CD148 exhibited a bleeding tendency and defective arterial thrombosis. Basal SFK activity was found to be markedly reduced in CD148-deficient platelets, resulting in a global hyporesponsiveness to agonists that signal through SFKs, including collagen and fibrinogen. G protein-coupled receptor responses to thrombin and other agonists were also marginally reduced. These results highlight CD148 as a global regulator of platelet activation and a novel antithrombotic drug target.

  16. The human endogenous circadian system causes greatest platelet activation during the biological morning independent of behaviors.

    Directory of Open Access Journals (Sweden)

    Frank A J L Scheer

    Full Text Available BACKGROUND: Platelets are involved in the thromboses that are central to myocardial infarctions and ischemic strokes. Such adverse cardiovascular events have day/night patterns with peaks in the morning (~9 AM, potentially related to endogenous circadian clock control of platelet activation. The objective was to test if the human endogenous circadian system influences (1 platelet function and (2 platelet response to standardized behavioral stressors. We also aimed to compare the magnitude of any effects on platelet function caused by the circadian system with that caused by varied standardized behavioral stressors, including mental arithmetic, passive postural tilt and mild cycling exercise. METHODOLOGY/PRINCIPAL FINDINGS: We studied 12 healthy adults (6 female who lived in individual laboratory suites in dim light for 240 h, with all behaviors scheduled on a 20-h recurring cycle to permit assessment of endogenous circadian function independent from environmental and behavioral effects including the sleep/wake cycle. Circadian phase was assessed from core body temperature. There were highly significant endogenous circadian rhythms in platelet surface activated glycoprotein (GP IIb-IIIa, GPIb and P-selectin (6-17% peak-trough amplitudes; p ≤ 0.01. These circadian peaks occurred at a circadian phase corresponding to 8-9 AM. Platelet count, ATP release, aggregability, and plasma epinephrine also had significant circadian rhythms but with later peaks (corresponding to 3-8 PM. The circadian effects on the platelet activation markers were always larger than that of any of the three behavioral stressors. CONCLUSIONS/SIGNIFICANCE: These data demonstrate robust effects of the endogenous circadian system on platelet activation in humans--independent of the sleep/wake cycle, other behavioral influences and the environment. The 9 AM timing of the circadian peaks of the three platelet surface markers, including platelet surface activated GPIIb-IIIa, the

  17. The nature of interactions between tissue-type plasminogen activator and platelets

    Energy Technology Data Exchange (ETDEWEB)

    Torr, S.R.; Winters, K.J.; Santoro, S.A.; Sobel, B.E. (Washington Univ., St. Louis, MO (USA))

    1990-07-15

    To elucidate interactions responsible for inhibition of aggregation of platelets in platelet-rich plasma (PRP) harvested from whole blood preincubated with t-PA, experiments were performed with PRP and washed platelets under diverse conditions of preincubation. Both ADP and collagen induced aggregation were inhibited in PRP unless aprotinin had been added to the preincubated whole blood concomitantly with t-PA. However, in washed platelets prepared after the same exposure aggregation was intact. When washed platelets were supplemented with fibrinogen degradation products (FDPs) in concentrations simulating those in whole blood preincubated with t-PA, aggregation induced with either ADP or collagen was inhibited. Thus, the inhibition in PRP depended on generation of FDPs by activated plasminogen. The functional integrity of surface glycoprotein (GP) IIb/IIIa receptors in washed platelets was documented by autoradiography after SDS-PAGE of surface labeled GPs and by fibrinogen binding despite preincubation of the whole blood or washed platelets themselves with t-PA and plasminogen as long as exogenous calcium (greater than or equal to 0.1 microM) was present. In contrast, when calcium was absent, the platelet GP IIb/IIIa receptor was rendered susceptible to degradation by plasmin, and aggregation was inhibited by preincubation at 37 degrees C even if aprotinin was present when aggregation was being assayed. These observations reconcile disparate results in the literature from studies in vivo and in vitro by demonstrating that inhibition of aggregation of platelets in PRP and in whole blood reflects indirect effects of plasminogen activation rather than direct effects of t-PA or plasmin on the platelets themselves.

  18. Synthesis and Vasorelaxant and Platelet Antiaggregatory Activities of a New Series of 6-Halo-3-phenylcoumarins

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    Dolores Viña

    2010-01-01

    Full Text Available A series of 6-halo-3-hydroxyphenylcoumarins (resveratrol-coumarins hybrid derivatives was synthesized in good yields by a Perkin reaction followed by hydrolysis. The new compounds were evaluated for their vasorelaxant activity in intact rat aorta rings pre-contracted with phenylephrine (PE, as well as for their inhibitory effects on platelet aggregation induced by thrombin in washed human platelets. These compounds concentration-dependently relaxed vascular smooth muscle and some of them showed a platelet antiaggregatory activity that was up to thirty times higher than that shown by trans-resveratrol and some other previously synthesized derivatives.

  19. Intracellular matrix metalloproteinase-2 (MMP-2) regulates human platelet activation via hydrolysis of talin.

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    Soslau, Gerald; Mason, Christopher; Lynch, Stephen; Benjamin, James; Ashak, Dani; Prakash, Jamunabai M; Moore, Andrew; Bagsiyao, Pamela; Albert, Trevine; Mathew, Lynn M; Jost, Monika

    2014-01-01

    Matrix metalloproteinase (MMP) activity is generally associated with normal or pathological extracellular processes such as tissue remodelling in growth and development or in tumor metastasis and angiogenesis. Platelets contain at least three MMPs, 1, 2 and 9 that have been reported to stimulate or inhibit agonist-induced platelet aggregation via extracellular signals. The non-selective Zn+2 chelating MMP inhibitor, 1,10-phenanthroline, and the serine protease inhibitor, AEBSF, were found to inhibit all tested agonist-induced platelet aggregation reactions. In vitro analysis demonstrated that 1,10-phenanthroline completely inhibited MMP-1,2,and 9 but had little to no effect on calpain activity while the converse was true with AEBSF. We now demonstrate that MMP-2 functions intracellularly to regulate agonist-induced platelet aggregations via the hydrolytic activation of talin, the presumed final activating factor of glycoprotein (GP)IIb/IIIa integrin (the inside-out signal). Once activated GPIIb/IIIa binds the dimeric fibrinogen molecule required for platelet aggregation. The active intracellular MMP-2 molecule is complexed with JAK 2/STAT 3, as demonstrated by the fact that all three proteins are co-immunoprecipitated with either anti-JAK 2, or anti-STAT 3 antibodies and by immunofluorescence studies. The MMP-2 platelet activation pathway can be synergistically inhibited with the non-selective MMP inhibitor, 1,10-phenanthroline, plus a JAK 2 inhibitor. This activation pathway is distinct from the previously reported calpain-talin activating pathway. The identification of a new central pathway for platelet aggregation presents new potential targets for drug regulation and furthers our understanding of the complexity of platelet activation mechanisms.

  20. Angiogenesis, Inflammation, Platelets Count, and Metastatic Status as a Predictor for Thrombosis Risk in Nasopharyngeal Carcinoma Patients

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    Aru W Sudoyo

    2015-03-01

    Full Text Available Aim: to assess the use of of angiogenesis, inflammation, platelets count, and metastatic status as predictors for thrombosis risk represented by soluble P-selectin level in nasopharyngeal carcinoma (NPC patients. Methods: a cross sectional study was conducted on NPC patients at the Hematology and Oncology Clinic of Cipto Mangunkusumo Hospital, Jakarta, during Mei to October 2012. Data regarding angiogenesis (CD105 and VEGFR-2, inflammation (IL-6, platelets count, and metastatic status were assessed at enrollment, as well as soluble P-selectin levels in all eligible patients. Bivariate analysis continued with multiple linear regression analysis were done to identify independent predictors for soluble P-selectin levels. Results: sixty NPC patients were enrolled in the study. There was correlation between platelet counts (r=0.389; p=0.002, IL-6 (r=0.595; p<0.001 and number of metastatic sites (r=0.542; p<0.001 with soluble P-selectin level, and a linear regression analysis showed that these three variables can predict soluble P-selectin levels with adjusted R-square 65%. There was no correlation between VEGFR-2 and CD105 levels with soluble P-selectin levels.Conclusion: platelet counts, IL-6 level, and number of sites of metastasis can be used as predictors of soluble P-selectin level as parameter of thrombosis risk in NPC patients. Key words: nasopharyngeal carcinoma (NPC, thrombosis risk, soluble P-selectin.

  1. A novel role of sesamol in inhibiting NF-κB-mediated signaling in platelet activation

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    Chang Chao-Chien

    2011-12-01

    Full Text Available Abstract Background Platelet activation is relevant to a variety of coronary heart diseases. Our previous studies revealed that sesamol possesses potent antiplatelet activity through increasing cyclic AMP formation. Although platelets are anucleated cells, they also express the transcription factor, NF-κB, that may exert non-genomic functions in platelet activation. Therefore, we further investigated the inhibitory roles of sesamol in NF-κB-mediated platelet function. Methods Platelet aggregation, Fura 2-AM fluorescence, and immunoblotting analysis were used in this study. Results NF-κB signaling events, including IKKβ phosphorylation, IκBα degradation, and p65 phosphorylation, were markedly activated by collagen (1 μg/ml in washed human platelets, and these signaling events were attenuated by sesamol (2.5~25 μM. Furthermore, SQ22536 and ODQ, inhibitors of adenylate cyclase and guanylate cyclase, respectively, strongly reversed the sesamol (25 μM-mediated inhibitory effects of IKKβ phosphorylation, IκBα degradation, and p65 phosphorylation stimulated by collagen. The protein kinase A (PKA inhibitor, H89, also reversed sesamol-mediated inhibition of IκBα degradation. Moreover, BAY11-7082, an NF-κB inhibitor, abolished IκBα degradation, phospholipase C (PLCγ2 phosphorylation, protein kinase C (PKC activation, [Ca2+]i mobilization, and platelet aggregation stimulated by collagen. Preincubation of platelets with the inhibitors, SQ22536 and H89, both strongly reversed sesamol-mediated inhibition of platelet aggregation and [Ca2+]i mobilization. Conclusions Sesamol activates cAMP-PKA signaling, followed by inhibition of the NF-κB-PLC-PKC cascade, thereby leading to inhibition of [Ca2+]i mobilization and platelet aggregation. Because platelet activation is not only linked to hemostasis, but also has a relevant role in inflammation and metastasis, our data demonstrating that inhibition of NF-κB interferes with platelet function may

  2. Identification of platelet-activating factor acetylhydrolase II in human skin.

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    Marques, Mariangela; Pei, Yong; Southall, Michael D; Johnston, John M; Arai, Hiroyuki; Aoki, Junken; Inoue, Takao; Seltmann, Holger; Zouboulis, Christos C; Travers, Jeffrey B

    2002-10-01

    Platelet-activating factor acetylhydrolases are a family of specialized phospholipase A2 enzymes. They serve an anti-inflammatory function by converting the proinflammatory autocoid, PAF, into biologically inactive lyso-PAF, by the removal of the sn-2 acetyl group of this glycerophospholipid. Similarly, platelet-activating factor acetylhydrolases can also degrade oxidatively modified sn-2 polyunsaturated-fatty-acid-containing phospholipids, which are toxic to cells. Platelet-activating factor acetylhydrolase II is a recently cloned member of this family of specialized phospholipases. Consistent with a potential role of this intracellular enzyme in protecting membrane phospholipids against oxidative stress, platelet-activating factor acetylhydrolase II has been shown to translocate from cytosol to membranes in response to pro-oxidative stressors, and overexpression of this enzyme decreases the cytotoxic effects of these agents. The objective of this study was to assess whether platelet-activating factor acetylhydrolase II is involved in protecting skin against oxidative stress. Platelet-activating factor acetylhydrolase II protein was demonstrated in human skin by immunohistochemistry, with the highest levels of the enzyme found in sebaceous glands and lesser amounts in epidermal keratinocytes. Treatment of epidermal cells with t-butylhydroperoxide or ultraviolet B radiation resulted in platelet-activating factor acetylhydrolase II translocation from cytosol to membranes. To assess the role of this enzyme in epidermal function, a recombinant retroviral strategy was used to overexpress platelet-activating factor acetylhydrolase II in the human keratinocyte-derived cell line HaCaT. Overexpression of platelet-activating factor acetylhydrolase II protected HaCaT cells against apop tosis induced by oxidative stressors t-butylhydroperoxide and ultraviolet B radiation. Similar levels of apoptosis, however, were seen in both control and platelet-activating

  3. Role of platelet activating factor in pathogenesis of acute pancreatitis in rats.

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    Konturek, S J; Dembinski, A; Konturek, P J; Warzecha, Z; Jaworek, J; Gustaw, P; Tomaszewska, R; Stachura, J

    1992-01-01

    The importance of platelet activating factor in acute pancreatitis was examined by determining the tissue content of endogenous platelet activating factor and the protective effects of TCV-309, a highly selective platelet activating factor blocker, against caerulein induced pancreatitis in rats. Infusion of caerulein (10 micrograms/kg/h) for five hours resulted in about 70% increase in pancreatic weight, 22% rise in protein content, 50% reduction in tissue blood flow, nine fold increase in tissue level of platelet activating factor and 165% rise in plasma amylase as well as histological evidence of acute pancreatitis. Such infusion of caerulein in chronic pancreatic fistula rats caused a marked increase in protein output from basal secretion of 10 mg/30 minutes to 40 mg/30 minutes in the first hour of infusion followed by a decline in protein output to 15-20 mg/30 minutes in the following hours of the experiment. Exogenous platelet activating factor (50 micrograms/kg) injected ip produced similar alterations in weight, protein content, blood flow, and histology of the pancreas but the increment in serum amylase was significantly smaller and pancreatic secretion was reduced below the basal level. TCV-309 (50 micrograms/kg) given ip before caerulein or platelet activating factor administration significantly reduced the biochemical and morphological alterations caused by caerulein and abolished those induced by exogenous platelet activating factor. These results indicate that platelet activating factor plays an important role in the pathogenesis of acute pancreatitis probably by reducing the blood flow and increasing vascular permeability in the pancreas. PMID:1385272

  4. Detection value of Th17 related indexes and platelet activation indexes in patients with liver cancer

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    Pai-Qiang Chen; Qiao-Li Jiang; Jun Li; Jing Zhang

    2017-01-01

    Objective:To study the detection value of Th17 related indexes and platelet activation indexes in the patients with liver cancer.Methods: A total of 59 patients with liver cancer in our hospital from July 2015 to June 2016 were selected as the observation group, 59 healthy persons of the same ages with physical examination were selected as the control group, then the serum Th17 related indexes and platelet activation indexes levels of two groups were detected and compared, then the serum Th17 related indexes and platelet activation indexes levels of observation group with different stages and types of liver cancer were compared too. Results:The serum Th17 related indexes and platelet activation indexes levels of observation group were all higher than those of control group, the serum Th17 related indexes and platelet activation indexes levels of observation group with different stages and types of liver cancer had obvious differences (allP<0.05).Conclusions: The Th17 related indexes and platelet activation indexes of patients with liver cancer show higher expression state, and the expression levels of patients with different stages and types of liver cancer have obvious differences too, so the clinical detection value of those indexes in the patients with liver cancer are higher.

  5. Bacillus anthracis peptidoglycan activates human platelets through FcγRII and complement

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    Sun, Dawei; Popescu, Narcis I.; Raisley, Brent; Keshari, Ravi S.; Dale, George L.; Lupu, Florea

    2013-01-01

    Platelet activation frequently accompanies sepsis and contributes to the sepsis-associated vascular leakage and coagulation dysfunction. Our previous work has implicated peptidoglycan (PGN) as an agent causing systemic inflammation in gram-positive sepsis. We used flow cytometry and fluorescent microscopy to define the effects of PGN on the activation of human platelets. PGN induced platelet aggregation, expression of the activated form of integrin αIIbβ3, and exposure of phosphatidylserine (PS). These changes were dependent on immunoglobulin G and were attenuated by the Fcγ receptor IIa–blocking antibody IV.3, suggesting they are mediated by PGN–anti-PGN immune complexes signaling through Fcγ receptor IIa. PS exposure was not blocked by IV.3 but was sensitive to inhibitors of complement activation. PGN was a potent activator of the complement cascade in human plasma and caused deposition of C5b-9 on the platelet surface. Platelets with exposed PS had greatly accelerated prothrombinase activity. We conclude that PGN derived from gram-positive bacteria is a potent platelet agonist when complexed with anti-PGN antibody and could contribute to the coagulation dysfunction accompanying gram-positive infections. PMID:23733338

  6. Unfractionated and low-molecular-weight heparin and the phosphodiesterase inhibitors, IBMX and cilostazol, block ex vivo Equid Herpesvirus type-1-induced platelet activation

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    Tracy Stokol

    2016-11-01

    Full Text Available Equid herpes virus type-1 (EHV-1 is a major pathogen of horses, causing abortion storms and outbreaks of herpes virus myeloencephalopathy. These clinical syndromes are partly attributed to ischemic injury from thrombosis in placental and spinal vessels. The mechanism of thrombosis in affected horses is unknown. We have previously shown that EHV-1 activates platelets through virus-associated tissue factor-initiated thrombin generation. Activated platelets participate in thrombus formation by providing a surface to localize coagulation factor complexes that amplify and propagate thrombin generation. We hypothesized that coagulation inhibitors that suppress thrombin generation (heparins or platelet inhibitors that impede post-receptor thrombin signaling (phosphodiesterase [PDE] antagonists would inhibit EHV-1-induced platelet activation ex vivo. We exposed platelet-rich plasma collected from healthy horses to the RacL11 abortigenic and Ab4 neuropathogenic strains of EHV-1 at 1 plaque forming unit/cell in the presence or absence of unfractionated heparin (UFH, low-molecular-weight (LMWH heparin or the PDE inhibitors, 3-isobutyl-1methylxanthine (IBMX and cilostazol. We assessed platelet activation status in flow cytometric assays by measuring P-selectin expression. We found that all of the inhibitors blocked EHV-1- and thrombin-induced platelet activation in a dose-dependent manner. Platelet activation in PRP was maximally inhibited at concentrations of 0.05 U/mL UFH and 2.5 μg/mL LMWH. These concentrations represented 0.1 to 0.2 U/mL anti-Factor Xa activity measured in chromogenic assays. Both IBMX and cilostazol showed maximal inhibition of platelet activation at the highest tested concentration of 50 μM but inhibition was lower than that seen with UFH and LMWH. Our results indicate that heparin anticoagulants and strong non-selective (IBMX or isoenzyme-3 selective (cilostazol PDE antagonists inhibit ex vivo EHV-1-induced platelet activation

  7. MALT1-ubiquitination triggers non-genomic NF-κB/IKK signaling upon platelet activation.

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    Karim, Zubair A; Vemana, Hari Priya; Khasawneh, Fadi T

    2015-01-01

    We have recently shown that IKK complex plays an important non-genomic role in platelet function, i.e., regulates SNARE machinery-dependent membrane fusion. In this connection, it is well known that MALT1, whose activity is modulated by proteasome, plays an important role in the regulation of IKK complex. Therefore, the present studies investigated the mechanism by which IKK signaling is regulated in the context of the platelet proteasome. It was found that platelets express a functional proteasome, and form CARMA/MALT1/Bcl10 (CBM) complex when activated. Using a pharmacological inhibitor, the proteasome was found to regulate platelet function (aggregation, integrin activation, secretion, phosphatidylserine exposure and changes in intracellular calcium). It was also found to regulate thrombogenesis and physiologic hemostasis. We also observed, upon platelet activation, that MALT1 is ubiquitinated, and this coincides with the activation of the IKK/NF-κB-signaling pathway. Finally, we observed that the proteasome inhibitor blocks CBM complex formation and the interaction of IKKγ and MALT1; abrogates SNARE formation, and the association of MALT1 with TAK1 and TAB2, which are upstream of the CBM complex. Thus, our data demonstrate that MALT1 ubiquitination is critical for the engagement of CBM and IKK complexes, thereby directing platelet signals to the NF-κB pathway.

  8. MALT1-ubiquitination triggers non-genomic NF-κB/IKK signaling upon platelet activation.

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    Zubair A Karim

    Full Text Available We have recently shown that IKK complex plays an important non-genomic role in platelet function, i.e., regulates SNARE machinery-dependent membrane fusion. In this connection, it is well known that MALT1, whose activity is modulated by proteasome, plays an important role in the regulation of IKK complex. Therefore, the present studies investigated the mechanism by which IKK signaling is regulated in the context of the platelet proteasome. It was found that platelets express a functional proteasome, and form CARMA/MALT1/Bcl10 (CBM complex when activated. Using a pharmacological inhibitor, the proteasome was found to regulate platelet function (aggregation, integrin activation, secretion, phosphatidylserine exposure and changes in intracellular calcium. It was also found to regulate thrombogenesis and physiologic hemostasis. We also observed, upon platelet activation, that MALT1 is ubiquitinated, and this coincides with the activation of the IKK/NF-κB-signaling pathway. Finally, we observed that the proteasome inhibitor blocks CBM complex formation and the interaction of IKKγ and MALT1; abrogates SNARE formation, and the association of MALT1 with TAK1 and TAB2, which are upstream of the CBM complex. Thus, our data demonstrate that MALT1 ubiquitination is critical for the engagement of CBM and IKK complexes, thereby directing platelet signals to the NF-κB pathway.

  9. The modulation of platelet adhesion and activation by chitosan through plasma and extracellular matrix proteins.

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    Lord, Megan S; Cheng, Bill; McCarthy, Simon J; Jung, MoonSun; Whitelock, John M

    2011-10-01

    Chitosan has been shown to promote initial wound closure events to prevent blood loss. Platelet adhesion and activation are crucial early events in these processes after traumatic bleeding leading to thrombus formation. Platelet adhesion to chitosan was found to be enhanced in the presence of adsorbed plasma and extracellular matrix proteins and was found to be primarily mediated by α(IIb)β(3) integrins, while α(2)β(1) integrins were found to be involved in platelet adhesion to collagen and perlecan. Platelets were found to be activated by chitosan, as shown by an increase in the expression of α(IIb)β(3) integrins and P-selectin, while the extent of activation was modulated by the presence of proteins including perlecan and fibrinogen. Collagen-coated chitosan was found to activate platelets to the same extent as either chitosan or collagen alone. These data support the role of plasma and extracellular matrix proteins in promoting chitosan mediated platelet adhesion and activation supporting the hypothesis that chitosan promotes wound healing via these interactions.

  10. The impact of vitamin C on the relationship among inflammation, lipid peroxidation, and platelet activation during analgesic nephropathy in rats.

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    Hadzi-Petrushev, Nikola; Mitrov, Dine; Kostovski, Vladimir; Mladenov, Mitko

    2017-08-03

    Oxidative stress and inflammation are involved in the pathogenesis of paracetamol-induced renal damage. This study examines the relationship between 8-iso-prostaglandin F2α (8-iso-PGF2α) and platelet activation as well as the relative contribution of the pro-inflammatory markers interleukin (IL)-1β and tumor necrosis factor-α (TNF-α) in enhanced 8-iso-PGF2α biosynthesis, as a complementary onset during analgesic nephropathy induced by chronic treatment with paracetamol. The protective effects of vitamin C on the aforementioned settings are also investigated. Analgesic nephropathy was induced in Wistar rats. Renal function markers and the activity of antioxidant enzymes were determined spectrophotometrically. Immunoassays were used to measure the pro-inflammatory markers and the markers of lipid peroxidation and platelet activation. The chronic treatment with paracetamol led to renal dysfunction, represented by the elevation of plasma urea and creatinine and the decline in the enzymatic antioxidant status, but did not cause a significant increase in TNF-α and IL-1β. The paracetamol-induced lipid peroxidation and enhanced production of 8-iso-PGF2α was not sufficient to cause changes in platelet activation represented by the level of 11-dehydro thromboxane B2. Our results suggest that oxidative stress cannot circumvent the need of stimulation by circulatory cytokines in order to induce inflammatory response and changes in platelet activation during analgesic nephropathy. Vitamin C proved to be beneficial in restoring the renal function markers to normal, increasing the renal enzymatic antioxidant potential, inhibiting lipid peroxidation, and lowering cytokine production and 11-dehydro thromboxane B2 excretion. The observed effects of vitamin C offer support for its potential use as protective treatment in cases of chronic paracetamol overdose.

  11. Surface morphology of platelet adhesion influenced by activators, inhibitors and shear stress

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    Watson, Melanie Groan

    Platelet activation involves multiple events, one of which is the generation and release of nitric oxide (NO), a platelet aggregation inhibitor. Platelets simultaneously send and receive various agents that promote a positive and negative feedback control system during hemostasis. Although the purpose of platelet-derived NO is not fully understood, NO is known to inhibit platelet recruitment. NO's relatively large diffusion coefficient allows it to diffuse more rapidly than platelet agonists. It may thus be able to inhibit recruitment of platelets near the periphery of a growing thrombus before agonists have substantially accumulated in those regions. Results from two studies in our laboratory differed in the extent to which platelet-derived NO decreased platelet adhesion. Frilot studied the effect of L-arginine (L-A) and NG-Methyl-L-arginine acetate salt (L-NMMA) on platelet adhesion to collagen under static conditions in a Petri dish. Eshaq examined the percent coverage on collagen-coated and fibrinogen-coated microchannels under shear conditions with different levels of L-A and Adenosine Diphosphate (ADP). Frilot's results showed no effect of either L-A or L-NMMA on surface coverage, thrombus size or serotonin release, while Eshaq's results showed a decrease in surface coverage with increased levels of L-A. A possible explanation for these contrasting results is that platelet-derived NO may be more important under flow conditions than under static conditions. For this project, the effects of L-A. ADP and L-NMMA on platelet adhesion were studied at varying shear stresses on protein-coated glass slides. The surface exposed to platelet-rich-plasma in combination with each chemical solution was observed under AFM, FE-SEM and fluorescence microscopy. Quantitative and qualitative comparisons of images obtained with these techniques confirmed the presence of platelets on the protein coatings. AFM images of fibrinogen and collagen-coated slides presented characteristic

  12. Circulating platelet-neutrophil complexes are important for subsequent neutrophil activation and migration.

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    Kornerup, Kristin N; Salmon, Gary P; Pitchford, Simon C; Liu, Wai L; Page, Clive P

    2010-09-01

    Previous studies in our laboratory have shown that platelets are essential for the migration of eosinophils into the lungs of allergic mice, and that this is dependent on the functional expression of platelet P-selectin. We sought to investigate whether the same is true for nonallergic, acute inflammatory stimuli administered to distinct anatomic compartments. Neutrophil trafficking was induced in two models, namely zymosan-induced peritonitis and LPS-induced lung inflammation, and the platelet dependence of these responses investigated utilizing mice rendered thrombocytopenic. The relative contribution of selectins was also investigated. The results presented herein clearly show that platelet depletion (>90%) significantly inhibits neutrophil recruitment in both models. In addition, we show that P-selectin glycoprotein ligand-1, but not P-selectin, is essential for neutrophil recruitment in mice in vivo, thus suggesting the existence of different regulatory mechanisms for the recruitment of leukocyte subsets in response to allergic and nonallergic stimuli. Further studies in human blood demonstrate that low-dose prothrombotic and pro-inflammatory stimuli (CCL17 or CCL22) synergize to induce platelet and neutrophil activation, as well as the formation of platelet-neutrophil conjugates. We conclude that adhesion between platelets and neutrophils in vivo is an important event in acute inflammatory responses. Targeting this interaction may be a successful strategy for inflammatory conditions where current therapy fails to provide adequate treatment.

  13. Platelet activation biomarkers in Berkeley sickle cell mice and the response to prasugrel.

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    Ohno, Kousaku; Tanaka, Hisako; Samata, Naozumi; Jakubowski, Joseph A; Tomizawa, Atsuyuki; Mizuno, Makoto; Sugidachi, Atsuhiro

    2014-10-01

    Vaso-occlusive crisis (VOC) is a common complication that occurs in sickle cell disease (SCD) patients. Although underlying mechanisms of VOC remain unclear, platelet activation has been associated with VOC. In the present study, plasma adenine nucleotide measurements using LC-ESI-MS/MS showed that plasma ADP in the Berkeley murine model of SCD was significantly higher (applox. 2.7-fold increase) compared with control mice. Assessment of platelet activation markers using flow cytometry indicated that in SCD mice at steady state (8 weeks old), circulating platelets were partially activated and this tended to increase with age (15 weeks old). The administration of prasugrel, a thienopiridyl P2Y12 antagonist, did not affect the activation state of circulating platelets suggesting P2Y12 independent mechanism of activation. In this murine SCD model, ex vivo addition of ADP or PAR4 TRAP resulted in further platelet activation as assessed by expression of activated GPIIb/IIIa and P-selectin both at 8 and 15 weeks. In 15 weeks old SCD mice, agonist-induced increases in activation markers were enhanced compared to control mice. Oral administration of prasugrel effectively inhibited ex vivo platelet activation consistent with clinical data in patients with SCD. In conclusion, in the Berkeley murine model of SCD, we found evidence of basal and agonist-stimulated platelet activation which could in part be attenuated by prasugrel. These data are consistent with observations made in patients with SCD and suggest possible utility of this murine model and prasugrel therapy in exploring treatment options for patients with SCD.

  14. Platelet activation attracts a subpopulation of effector monocytes to sites of Leishmania major infection.

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    Goncalves, Ricardo; Zhang, Xia; Cohen, Heather; Debrabant, Alain; Mosser, David M

    2011-06-01

    Leishmania species trigger a brisk inflammatory response and efficiently induce cell-mediated immunity. We examined the mechanisms whereby leukocytes were recruited into lesions after Leishmania major infection of mice. We found that a subpopulation of effector monocytes expressing the granulocyte marker GR1 (Ly6C) is rapidly recruited into lesions, and these monocytes efficiently kill L. major parasites. The recruitment of this subpopulation of monocytes depends on the chemokine receptor CCR2 and the activation of platelets. Activated platelets secrete platelet-derived growth factor, which induces the rapid release of CCL2 from leukocytes and mesenchymal cells. This work points to a new role for platelets in host defense involving the selective recruitment of a subpopulation of effector monocytes from the blood to efficiently kill this intracellular parasite.

  15. Stimulation of Toll-like receptor 2 in human platelets induces a thromboinflammatory response through activation of phosphoinositide 3-kinase.

    Science.gov (United States)

    Blair, Price; Rex, Sybille; Vitseva, Olga; Beaulieu, Lea; Tanriverdi, Kahraman; Chakrabarti, Subrata; Hayashi, Chie; Genco, Caroline A; Iafrati, Mark; Freedman, Jane E

    2009-02-13

    Cells of the innate immune system use Toll-like receptors (TLRs) to initiate the proinflammatory response to microbial infection. Recent studies have shown acute infections are associated with a transient increase in the risk of vascular thrombotic events. Although platelets play a central role in acute thrombosis and accumulating evidence demonstrates their role in inflammation and innate immunity, investigations into the expression and functionality of platelet TLRs have been limited. In the present study, we demonstrate that human platelets express TLR2, TLR1, and TLR6. Incubation of isolated platelets with Pam(3)CSK4, a synthetic TLR2/TLR1 agonist, directly induced platelet aggregation and adhesion to collagen. These functional responses were inhibited in TLR2-deficient mice and, in human platelets, by pretreatment with TLR2-blocking antibody. Stimulation of platelet TLR2 also increased P-selectin surface expression, activation of integrin alpha(IIb)beta(3), generation of reactive oxygen species, and, in human whole blood, formation of platelet-neutrophil heterotypic aggregates. TLR2 stimulation also activated the phosphoinositide 3-kinase (PI3-K)/Akt signaling pathway in platelets, and inhibition of PI3-K significantly reduced Pam(3)CSK4-induced platelet responses. In vivo challenge with live Porphyromonas gingivalis, a Gram-negative pathogenic bacterium that uses TLR2 for innate immune signaling, also induced significant formation of platelet-neutrophil aggregates in wild-type but not TLR2-deficient mice. Together, these data provide the first demonstration that human platelets express functional TLR2 capable of recognizing bacterial components and activating the platelet thrombotic and/or inflammatory pathways. This work substantiates the role of platelets in the immune and inflammatory response and suggests a mechanism by which bacteria could directly activate platelets.

  16. Response to platelet-activating factor in human platelets stored and aged in plasma. Decrease in aggregation, phosphoinositide turnover, and receptor affinity

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    Shukla, S.D.; Morrison, W.J.; Klachko, D.M.

    1989-07-01

    Human platelet concentrates were stored in polyolefin bags at 22 to 24 degrees C on a horizontal shaker for up to 8 days. At different intervals, aliquots of platelet-rich plasma (PRP) were removed aseptically and five variables, i.e., platelet counts, morphology, platelet-activating factor (PAF)-stimulated aggregation, phosphoinositide turnover, and (3H)PAF binding to platelet receptors, were studied. The number of platelets did not change during the 8 days of storage. Scanning electron microscopy of the platelets revealed a gradual morphologic change from biconcave flat discs to irregular, crenated forms. The PAF-induced aggregation of platelets declined with time of storage. A decrease to 50 percent of the Day 1 aggregatory response to PAF was evident on Day 2, and there was a further decline to about 20 percent by Day 6. Similarly, PAF receptor-coupled phosphoinositide turnover, as monitored by 32P incorporation into individual phosphoinositides, decreased dramatically with storage. After 2 to 3 days of storage, the phosphoinositide turnover was reduced to 50 percent of the original response, and it continued to decline to about 25 percent of original response by Day 5 or 6. The binding of (3H)PAF to washed human platelets indicated subtle changes between Days 2 and 4, which became more noticeable by Day 6. These results have raised the possibility of changes in the number of the receptors and/or their affinity for the ligand during storage. We conclude that although the number of platelets was maintained during storage for 8 days, a general deterioration of their responses to PAF occurred at the levels of cell surface receptor, transmembrane signaling (phosphoinositide turnover), and response (aggregation).

  17. Influence of red algal sulfated polysaccharides on blood coagulation and platelets activation in vitro.

    Science.gov (United States)

    Sokolova, Ekaterina V; Byankina, Anna O; Kalitnik, Alexandra A; Kim, Yong H; Bogdanovich, Larisa N; Solov'eva, Tamara F; Yermak, Irina M

    2014-05-01

    The influence of sulfated polysaccharides (λ-, κ-, and κ/β-carrageenan and porphyran) - on platelet activation was studied. Carrageenans were much weaker inhibitors of a coagulation process than heparin, while porphyran had not that effect. Results of the aPTT and PT assays suppose that carrageenans affected mostly intrinsic pathway of coagulation, while their effect on the extrinsic pathway is extremely low (λ and κ/β) or absent (κ, LMW derivative of κ-carrageenan). λ-Carrageenan was the most potent anticoagulant agent in TT, aPTT, PT, and anti-factor Xa activity. This sample was also the strongest inhibitor of collagen-induced platelet aggregation in PRP. Generally, the correlation of anticoagulant and antithrombotic action in PRP is preserved for carrageenans but not for heparin. Carrageenans and porphyran affected platelet adhesion to collagen by influencing glycoprotein VI. Low molecular weight κ-carrageenan had a similar effect on platelet adhesion mediated with both major collagen receptors: integrin α2 β1 and glycoprotein VI as native polysaccharide had. Carrageenans resulted in activation of platelets under platelet adhesion mediated by integrin αIIb β3 with less degree than heparin. The least sulfated κ/β-carrageenan that possessed an inhibiting effect on thrombin- and collagen-induced aggregation of washed platelets and on the PT test but it had no significant effect on TT was the weakest promoter of integrin αIIb β3 mediated platelet activation. In summary, our study showed that the polysaccharide action was complex, since it depended on its molecular mass, sulfation degree, and monosaccharide contents (3,6-anhydrogalactose).

  18. Platelet lipidomic.

    Science.gov (United States)

    Dolegowska, B; Lubkowska, A; De Girolamo, L

    2012-01-01

    Lipids account for 16-19 percent dry platelet matter and includes 65 percent phospholipids, 25 percent neutral lipids and about 8 percent glycosphingolipids. The cell membrane that surrounds platelets is a bilayer that contains different types phospholipids symmetrically distributed in resting platelets, such as phosphatidylserine (PS), phosphatidylethanolamine (PE), phosphatidylcholine, and sphingomyelin. The collapse of lipid asymmetry is exposure of phosphatidylserine in the external leaflet of the plasma bilayer, where it is known to serve at least two major functions: providing a platform for development of the blood coagulation cascade and presenting the signal that induces phagocytosis of apoptotic cells. During activation, this asymmetrical distribution becomes disrupted, and PS and PE become exposed on the cell surface. The transbilayer movement of phosphatidylserine is responsible for the platelet procoagulant activity. Exposure of phosphatidylserine is a flag for macrophage recognition and clearance from the circulation. Platelets, stored at room temperature for transfusion for more than 5 days, undergo changes collectively known as platelet storage lesions. Thus, the platelet lipid composition and its possible modifications over time are crucial for efficacy of platelet rich plasma therapy. Moreover, a number of substances derived from lipids are contained into platelets. Eicosanoids are lipid signaling mediators generated by the action of lipoxygenase and include prostaglandins, thromboxane A2, 12-hydroxyeicosatetraenoic acid. Isoprostanes have a chemical structure similar to this of prostanoids, but are differently produced into the particle, and are ligands for prostaglandins receptors, exhibiting biological activity like thromboxane A2. Endocannabinoids are derivatives from arachidonic acid which could reduce local pain. Phospholipids growth factors (sphingolipids, lysophosphatidic acid, platelet-activating factor) are involved in tissue

  19. The role of platelet and plasma markers of antioxidant status and oxidative stress in thrombocytopenia among patients with vivax malaria

    Directory of Open Access Journals (Sweden)

    Claudio F Araujo

    2008-09-01

    Full Text Available Malaria remains an important health problem in tropical countries like Brazil. Thrombocytopenia is the most common hematological disturbance seen in malarial infection. Oxidative stress (OS has been implicated as a possible mediator of thrombocytopenia in patients with malaria. This study aimed to investigate the role of OS in the thrombocytopenia of Plasmodium vivax malaria through the measurement of oxidant and antioxidant biochemical markers in plasma and in isolated platelets. Eighty-six patients with P. vivax malaria were enrolled. Blood samples were analyzed for total antioxidant and oxidant status, albumin, total protein, uric acid, zinc, magnesium, bilirubin, total thiols, glutathione peroxidase (GPx, malondialdehyde (MDA, antibodies against mildly oxidized low-density lipoproteins (LDL-/nLDL ratio and nitrite/nitrate levels in blood plasma and GPx and MDA in isolated platelets. Plasma MDA levels were higher in thrombocytopenic (TCP (median 3.47; range 1.55-12.90 µmol/L compared with the non-thrombocytopenic (NTCP patients (median 2.57; range 1.95-8.60 µmol/L. Moreover, the LDL-/nLDL autoantibody ratio was lower in TCP (median 3.0; range 1.5-14.8 than in NTCP patients (median 4.0; range 1.9-35.5. Finally, GPx and MDA were higher in the platelets of TPC patients. These results suggest that oxidative damage of platelets might be important in the pathogenesis of thrombocytopenia found in P. vivax malaria as indicated by alterations of GPx and MDA.

  20. Real-time monitoring of the functional status of platelets treated by Infukoll using a computer-aided laser phase microscope

    Science.gov (United States)

    Vasilenko, Irina A.; Babakova, Svetlana; Kiseleva, Elena; Dyugeev, Adyan; Konradov, Alexander A.; Shabalin, Vladimir

    1999-02-01

    Combined analysis of optic-geometrical characteristics makes it possible to comprehensively evaluate the morphological and functional state of the cytological object, which can not be done during visual observation. The technique is discussed for real-time monitoring of the functional status of platelets using computer-aided phase microscope (CPM) 'Cytoscan'. High accuracy and sensitivity of CPM with respect to determination of local temporal phase make it possible to register the dynamic processes in the voluntarily chosen points and sections of micro-objects, to obtain the Fourier's spectra and other characteristics suitable for statistical analysis. Human platelets were prepared from venous blood of healthy donors and pregnant women by standard methods, suspended in culture medium 199 and treated by different doses of 6% Infukoll HES. Nonfixating and nonstaining cells were studied with CPM: height accuracy 0.5 nm, magnification 1000, acquisition time 4 - 30 s. In our experiments we used time resolution about 0.03 s and 30 x lens with numerical aperture 0.65. During investigations of temporal processes a certain section was chosen in the topogram of cell image and local values for the phase of scattered wave in each of the points of the chosen cell's profile were measured. On the basis of the results of automated phase image analysis of optic-geometrical characteristics of living cells, the new quantitative express-method for evaluating of the functional status of human platelets was developed and tested. The structural changes of cells were visualized in alteration of 3-D images, phase profiles, in the decrease of mean cell phase diameters, heights, volumes, in disturbance of histograms of phase heights distribution by cell image points. New data on the behavior of platelets treated by Infukoll in vitro and in vivo were obtained. Analysis of intracellular dynamics was allowed to characterize the cell's regions of maximal activity, but the intensity of processes

  1. Activated platelets from diabetic rats cause endothelial dysfunction by decreasing Akt/endothelial NO synthase signaling pathway.

    Directory of Open Access Journals (Sweden)

    Keiko Ishida

    Full Text Available Diabetes is associated with endothelial dysfunction and platelet activation, both of which may contribute to increased cardiovascular risk. The purpose of this study was to characterize circulating platelets in diabetes and clarify their effects on endothelial function. Male Wistar rats were injected with streptozotocin (STZ to induce diabetes. Each experiment was performed by incubating carotid arterial rings with platelets (1.65×10(7 cells/mL; 30 min isolated from STZ or control rats. Thereafter, the vascular function was characterized in isolated carotid arterial rings in organ bath chambers, and each expression and activation of enzymes involved in nitric oxide and oxidative stress levels were analyzed. Endothelium-dependent relaxation induced by acetylcholine was significantly attenuated in carotid arteries treated with platelets isolated from STZ rats. Similarly, treatment with platelets isolated from STZ rats significantly reduced ACh-induced Akt/endothelial NO synthase signaling/NO production and enhanced TXB2 (metabolite of TXA2, while CD61 (platelet marker and CD62P (activated platelet marker were increased in carotid arteries treated with platelets isolated from STZ rats. Furthermore, the platelets isolated from STZ rats decreased total eNOS protein and eNOS dimerization, and increased oxidative stress. These data provide direct evidence that circulating platelets isolated from diabetic rats cause dysfunction of the endothelium by decreasing NO production (via Akt/endothelial NO synthase signaling pathway and increasing TXA2. Moreover, activated platelets disrupt the carotid artery by increasing oxidative stress.

  2. Cystic fibrosis heterozygotes do not have increased platelet activation

    DEFF Research Database (Denmark)

    Tarnow, Inge; Michelson, Alan D.; Frelinger III, Andrew L.;

    2007-01-01

    Introduction: We have previously demonstrated platelet hyperreactivity in cystic fibrosis (CF) patients. Carriers of one CF m utation (heterozygotes) have been shown to have abnormalities related to the presence of only one-half the normal amount of CF transmembrane conductance regulator protein...

  3. Establishment of Epithelial Attachment on Titanium Surface Coated with Platelet Activating Peptide

    Science.gov (United States)

    Sugawara, Shiho; Maeno, Masahiko; Lee, Cliff; Nagai, Shigemi; Kim, David M.; Da Silva, John; Kondo, Hisatomo

    2016-01-01

    The aim of this study was to produce epithelial attachment on a typical implant abutment surface of smooth titanium. A challenging complication that hinders the success of dental implants is peri-implantitis. A common cause of peri-implantitis may results from the lack of epithelial sealing at the peri-implant collar. Histologically, epithelial sealing is recognized as the attachment of the basement membrane (BM). BM-attachment is promoted by activated platelet aggregates at surgical wound sites. On the other hand, platelets did not aggregate on smooth titanium, the surface typical of the implant abutment. We then hypothesized that epithelial BM-attachment was produced when titanium surface was modified to allow platelet aggregation. Titanium surfaces were coated with a protease activated receptor 4-activating peptide (PAR4-AP). PAR4-AP coating yielded rapid aggregation of platelets on the titanium surface. Platelet aggregates released robust amount of epithelial chemoattractants (IGF-I, TGF-β) and growth factors (EGF, VEGF) on the titanium surface. Human gingival epithelial cells, when they were co-cultured on the platelet aggregates, successfully attached to the PAR4-AP coated titanium surface with spread laminin5 positive BM and consecutive staining of the epithelial tight junction component ZO1, indicating the formation of complete epithelial sheet. These in-vitro results indicate the establishment of epithelial BM-attachment to the titanium surface. PMID:27741287

  4. Activities of adenine nucleotide and nucleoside degradation enzymes in platelets of rats infected by Trypanosoma evansi.

    Science.gov (United States)

    Oliveira, Camila B; Da Silva, Aleksandro S; Vargas, Lara B; Bitencourt, Paula E R; Souza, Viviane C G; Costa, Marcio M; Leal, Claudio A M; Moretto, Maria B; Leal, Daniela B R; Lopes, Sonia T A; Monteiro, Silvia G

    2011-05-31

    Nucleotide and nucleoside-degrading enzymes, such as nucleoside triphosphate diphosphohydrose (NTPDase), 5'-nucleotidase and adenosine deaminase (ADA) are present in the surface membranes of platelets, involved in clotting disturbances of Trypanosoma evansi-infected animals. Thus, this study was aimed at evaluating the activities of these enzymes in platelets of rats experimentally infected with T. evansi. Animals were divided into four groups, according to the level of parasitemia. Blood samples were collected on days 3 (group A: at the beginning of parasitemia), 5 (group B: high parasitemia) and 15 (group C: chronic infection), post-infection. Group D (control group) was composed of non-infected animals for platelet count, separation and enzymatic assays. Animals from groups A and B showed marked thrombocytopenia, but platelet count was not affected in chronically infected rats. NTPDase, 5'-nucleotidase and ADA activities decreased (pplatelets from rats of groups A and B, when compared to the control group. In group C, only NTPDase and 5'-nucleoside activities decreased (pplatelet count and nucleotide/nucleoside hydrolysis were positive and statistically significant (pPlatelet aggregation was decreased in all infected groups, in comparison to the control group (pplatelets of T. evansi-infected animals might be related to thrombocytopenia, that by reducing the number of platelets, there was less release of ATP and ADP. Another possibility being suggested is that changes have occurred in the membrane of these cells, decreasing the expression of these enzymes in the cell membrane.

  5. Comparison of cytotoxic and anti-platelet activities of polyphenolic extracts from Arnica montana flowers and Juglans regia husks.

    Science.gov (United States)

    Rywaniak, Joanna; Luzak, Boguslawa; Podsedek, Anna; Dudzinska, Dominika; Rozalski, Marcin; Watala, Cezary

    2015-01-01

    Polyphenolic compounds of plant origin are well known to be beneficial to human health: they exert protective effects on haemostasis and have a particular influence on blood platelets. However, the anti-platelet properties of polyphenolic compounds observed so far have not been weighed against their potential cytotoxic action against platelets. The aim of this study was to demonstrate that anti-platelet and cytotoxic effects on blood platelets may interfere and therefore, may often lead to confusion when evaluating the properties of plant extracts or other agents towards blood platelets. The anti-platelet and cytotoxic in vitro effects of plant extracts obtained from the husks of walnuts (J. regia) and flowers of arnica (A. montana) on platelet reactivity and viability were examined. Platelet function was assessed using standard methods (flow cytometry: P-selectin expression, activation of GPIIbIIIa complex, vasodilator-stimulated phosphoprotein, VASP index; turbidimetric and impedance aggregometry) and newly set assays (flow cytometric monitoring of platelet cytotoxicity). The results reveal that none of the studied plant extracts demonstrated cytotoxicity towards blood platelets. The phenolic acid-rich extract of A. montana (7.5 and 15 µg/ml) significantly reduced the ADP-induced aggregation in both whole blood and PRP, and decreased the platelet reactivity index (PRI; VASP phosphorylation) in whole blood, while showing excellent antioxidant capacity. The extract of J. regia husks significantly reduced ADP-induced platelet aggregation in whole blood when applied at 7.5 µg/ml, and only slightly decreased the PRI at 15 µg/ml. Both examined extracts suppressed platelet hyper-reactivity, and such influence did not interfere with cytotoxic effects of the extracts. Thus, its high polyphenol content, excellent antioxidant capacity and distinct anti-platelet properties, in combination with its lack of toxicity, make the extract of A. montana flowers a possible

  6. Platelet proteomics.

    Science.gov (United States)

    Zufferey, Anne; Fontana, Pierre; Reny, Jean-Luc; Nolli, Severine; Sanchez, Jean-Charles

    2012-01-01

    Platelets are small cell fragments, produced by megakaryocytes, in the bone marrow. They play an important role in hemostasis and diverse thrombotic disorders. They are therefore primary targets of antithrombotic therapies. They are implicated in several pathophysiological pathways, such as inflammation or wound repair. In blood circulation, platelets are activated by several pathways including subendothelial matrix and thrombin, triggering the formation of the platelet plug. Studying their proteome is a powerful approach to understand their biology and function. However, particular attention must be paid to different experimental parameters, such as platelet quality and purity. Several technologies are involved during the platelet proteome processing, yielding information on protein identification, characterization, localization, and quantification. Recent technical improvements in proteomics combined with inter-disciplinary strategies, such as metabolomic, transcriptomics, and bioinformatics, will help to understand platelets biological mechanisms. Therefore, a comprehensive analysis of the platelet proteome under different environmental conditions may contribute to elucidate complex processes relevant to platelet function regarding bleeding disorders or platelet hyperreactivity and identify new targets for antiplatelet therapy.

  7. Spacial isolation of protein kinase C activation in thrombin stimulated human platelets.

    Science.gov (United States)

    Crouch, M F; Lapetina, E G

    1988-10-14

    Thrombin stimulation of human platelets is associated with turnover of inositol phospholipids, mobilization of intracellular Ca2+ stores, and activation of protein kinase C. However, within 5 minutes, the thrombin receptor desensitizes, but can be re-coupled to its effectors by stimulation of alpha 2-adrenergic receptors (Crouch and Lapetina, J. Biol. Chem. 263, 3363-3371, 1988). This effect of epinephrine was found to be inhibited by preincubation of platelets with phorbol ester, suggesting that protein kinase C was inhibitory. However, since thrombin also activated protein kinase C and epinephrine was active following thrombin stimulation of platelets, this implied that thrombin activation of protein kinase C may have been spacially isolated near the thrombin receptor and could not inactivate alpha 2-receptor activity. In the present paper, we have tested this possibility, and we present evidence which strongly favours the possibility that protein kinase C activation by receptors induces its local translocation to the cell membrane.

  8. The effect of epoprostenol on platelet activation and consumption during experimental extracorporeal perfusion

    DEFF Research Database (Denmark)

    Skogby, M; Adrian, K; Friberg, L

    1999-01-01

    on the ECLS induced platelet consumption and activation. In terms of the methods, identical in vitro ECLS circuits were primed with fresh heparinized human blood and circulated for 24 h. Epoprostenol (2.4 microg/L blood/h) was added to one of the circuits in each pair. In total, 6 paired experiments were......Hemorrhages are major complications experienced in 10-35% of neonates treated with extracorporeal life support (ECLS). The increased bleeding tendency is partly due to an ECLS induced thrombocytopenia and impaired platelet function. In the present study, we evaluated the effect of epoprostenol......, no difference in the platelet membrane expression of GPIb and GPIIb/IIIa could be observed between the circuits. In conclusion, epoprostenol reduces platelet consumption during ECLS without affecting the membrane expression of GPIb and GPIIb/IIIa....

  9. The Role of Platelet-Activating Factor in Chronic Inflammation, Immune Activation, and Comorbidities Associated with HIV Infection

    Science.gov (United States)

    Kelesidis, Theodoros; Papakonstantinou, Vasiliki; Detopoulou, Paraskevi; Fragopoulou, Elizabeth; Chini, Maria; Lazanas, Marios C.; Antonopoulou, Smaragdi

    2016-01-01

    With the advent of highly effective antiretroviral therapy, cardiovascular disease has become an important cause of morbidity and mortality among people with treated HIV-1, but the pathogenesis is unclear. Platelet-activating factor is a potent lipid mediator of inflammation that has immunomodulatory effects and a pivotal role in the pathogenesis of inflammatory disorders and cardiovascular disease. Limited scientific evidence suggests that the platelet-activating factor pathway may be a mechanistic link between HIV-1 infection, systemic inflammation, and immune activation that contribute to pathogenesis of chronic HIV-related comorbidities, including cardiovascular disease and HIV-associated neurocognitive disorders. In this review, we examine the mechanisms by which the cross-talk between HIV-1, immune dysregulation, inflammation, and perturbations in the platelet-activating factor pathway may directly affect HIV-1 immunopathogenesis. Understanding the role of platelet-activating factor in HIV-1 infection may pave the way for further studies to explore therapeutic interventions, such as diet, that can modify platelet-activating factor activity and use of platelet-activating factor inhibitors that might improve the prognosis of HIV-1 infected patients. PMID:26616844

  10. Platelet activation and thrombus formation relates to the presence of myocardial inflammation in patients with cardiomyopathy.

    Science.gov (United States)

    Bobbert, Peter; Weikert, Ulf; Schmidt-Lucke, Caroline; Skurk, Carsten; Meyer, Alexander; Steffens, Daniel; Schultheiss, Heinz Peter; Rauch, Ursula

    2014-05-01

    Patients with cardiomyopathy show a significantly increased risk for thromboembolic events due to a hypercoagulable state and platelet dysfunction. The pathophysiologic mechanism underlying the increasing platelet activity in patients with cardiomyopathy remains unclear. We performed a clinical study to elucidate the link between myocardial tissue alterations and platelet activation in patients with cardiomyopathy. A total of 30 patients with suspected cardiomyopathy and 10 healthy control patients were included in our study. Hemodynamic parameters were measured by catheterization and echocardiography. Endomyocardial biopsies were taken to determine myocardial inflammation. Flow cytometry was performed to examine the platelet activation by quantification of p-selectin and thrombospondin expression on platelets. The p-selectin (8.46 ± 3.67 AU) and thrombospondin (26.56 ± 23.21 AU) expression was significantly correlated with the amount of CD3+ T cells (p-selectin: r=0.573, p<0.05; thrombospondin: r=0.488, p<0.05) and the endothelial/interstitial activation (p-selectin: r=0.521, p<0.05; thrombospondin: r=0.39, p<0.05). This was found to be independent of hemodynamic parameters, age, and gender. The platelet activation of patients (n=3) with echocardiographically documented ventricular thrombi was significantly increased (p-selectin: 12.57 ± 5.5 AU vs. 8.1 ± 3.2 AU, p<0.05) and this was associated with elevated myocardial inflammation scores. Myocardial inflammation is associated with a significant increase in platelet activation and ventricular thrombus formation independently of the hemodynamic conditions. Copyright © 2013 Japanese College of Cardiology. Published by Elsevier Ltd. All rights reserved.

  11. No evidence for a putative involvement of platelet-activating factor in systemic lupus erythematosus without active nephritis

    Directory of Open Access Journals (Sweden)

    Yves Denizot

    2003-01-01

    Full Text Available Background: Platelet-activating factor (PAF seems to be implicated in systemic lupus erythematosus (SLE patients with associated renal diseases.Aims: In this study, we ensured the role of PAF in SLE patients without renal complications.

  12. AMP-activated protein kinase (AMPK) regulates the insulin-induced activation of the nitric oxide synthase in human platelets.

    Science.gov (United States)

    Fleming, Ingrid; Schulz, Christian; Fichtlscherer, Birgit; Kemp, Bruce E; Fisslthaler, Beate; Busse, Rudi

    2003-11-01

    Little is known about the signaling cascades that eventually regulate the activity of the endothelial nitric oxide synthase (eNOS) in platelets. Here, we investigated the effects of insulin on the phosphorylation and activation of eNOS in washed human platelets and in endothelial cells. Insulin activated the protein kinase Akt in cultured endothelial cells and increased the phosphorylation of eNOS on Ser(1177) but failed to increase endothelial cyclic GMP levels or to elicit the relaxation of endothelium-intact porcine coronary arteries. In platelets, insulin also elicited the activation of Akt as well as the phosphorylation of eNOS and initiated NO production which was associated with increased cyclic GMP levels and the inhibition of thrombin-induced aggregation. The insulin-induced inhibition of aggregation was accompanied by a decreased Ca(2+) response to thrombin and was also prevented by N(omega) nitro-L-arginine. In platelets, but not in endothelial cells, insulin induced the activation of the AMP-activated protein kinase (AMPK), a metabolic stress-sensing kinase which was sensitive to the phosphatidylinositol 3-kinase (PI3-K) inhibitor wortmannin and the AMPK inhibitor iodotubercidin. Moreover, the insulin-mediated inhibition of thrombin-induced aggregation was prevented by iodotubercidin. Insulin-independent activation of the AMPK using 5-aminoimidazole-4-carboxamide ribonucleoside, increased platelet eNOS phosphorylation, increased cyclic GMP levels and attenuated platelet aggregation. These results highlight the differences in the signal transduction cascade activated by insulin in endothelial cells and platelets, and demonstrate that insulin stimulates the formation of NO in human platelets, in the absence of an increase in Ca(2+), by acti-vating PI3-K and AMPK which phosphorylates eNOS on Ser(1177).

  13. Influenza virus H1N1 activates platelets through FcγRIIA signaling and thrombin generation.

    Science.gov (United States)

    Boilard, Eric; Paré, Guillaume; Rousseau, Matthieu; Cloutier, Nathalie; Dubuc, Isabelle; Lévesque, Tania; Borgeat, Pierre; Flamand, Louis

    2014-05-01

    Platelets play crucial functions in hemostasis and the prevention of bleeding. During H1N1 influenza A virus infection, platelets display activation markers. The platelet activation triggers during H1N1 infection remain elusive. We observed that H1N1 induces surface receptor activation, lipid mediator synthesis, and release of microparticles from platelets. These activation processes require the presence of serum/plasma, pointing to the contribution of soluble factor(s). Considering that immune complexes in the H1N1 pandemic were reported to play a pathogenic role, we assessed their contribution in H1N1-induced platelet activation. In influenza-immunized subjects, we observed that the virus scaffolds with immunoglobulin G (IgG) to form immune complexes that promote platelet activation. Mechanistically, this activation occurs through stimulation of low-affinity type 2 receptor for Fc portion of IgG (FcγRIIA), a receptor for immune complexes, independently of thrombin. Using a combination of in vitro and in vivo approaches, we found that the antibodies from H3N2-immunized mice activate transgenic mouse platelets that express FcγRIIA when put in the presence of H1N1, suggesting that cross-reacting influenza antibodies suffice. Alternatively, H1N1 can activate platelets via thrombin formation, independently of complement and FcγRIIA. These observations identify both the adaptive immune response and the innate response against pathogens as 2 intertwined processes that activate platelets during influenza infections.

  14. Ingestion of onion soup high in quercetin inhibits platelet aggregation and essential components of the collagen-stimulated platelet activation pathway in man: a pilot study

    OpenAIRE

    Hubbard, G; Wolffram, S; Vos, de, W.M.; Bovy, A.G.; Gibbins, J.; Lovegrove, J

    2006-01-01

    Epidemiological data suggest that those who consume a diet rich in quercetin-containing foods may have a reduced risk of CVD. Furthermore, in vitro and ex vivo studies have observed the inhibition of collagen-induced platelet activation by quercetin. The aim of the present study was to investigate the possible inhibitory effects of quercetin ingestion from a dietary source on collagen-stimulated platelet aggregation and signalling. A double-blind randomised cross-over pilot study was undertak...

  15. Thrombin generation by activated factor VII on platelet activated by different agonists. Extending the cell-based model of hemostasis

    Directory of Open Access Journals (Sweden)

    Herrera Maria

    2006-04-01

    Full Text Available Abstract Background Platelet activation is crucial in normal hemostasis. Using a clotting system free of external tissue factor, we investigated whether activated Factor VII in combination with platelet agonists increased thrombin generation (TG in vitro. Methods and results TG was quantified by time parameters: lag time (LT and time to peak (TTP, and by amount of TG: peak of TG (PTG and area under thrombin formation curve after 35 minutes (AUC→35min in plasma from 29 healthy volunteers using the calibrated automated thrombography (CAT technique. TG parameters were measured at basal conditions and after platelet stimulation by sodium arachidonate (AA, ADP, and collagen (Col. In addition, the effects of recombinant activated FVII (rFVIIa alone or combined with the other platelet agonists on TG parameters were investigated. We found that LT and TTP were significantly decreased (p 35min were significantly increased (p 35min (but not PTG when compared to platelet rich plasma activated with agonists in the absence of rFVIIa. Conclusion Platelets activated by AA, ADP, Col or rFVIIa triggered TG. This effect was increased by combining rFVIIa with other agonists. Our intrinsic coagulation system produced a burst in TG independent of external tissue factor activity an apparent hemostatic effect with little thrombotic capacity. Thus we suggest a modification in the cell-based model of hemostasis.

  16. Platelet aggregation and serum adenosine deaminase (ADA) activity in pregnancy associated with diabetes, hypertension and HIV.

    Science.gov (United States)

    Leal, Claudio A M; Leal, Daniela B R; Adefegha, Stephen A; Morsch, Vera M; da Silva, José E P; Rezer, João F P; Schrekker, Clarissa M L; Abdalla, Faida H; Schetinger, Maria R C

    2016-07-01

    Platelet aggregation and adenosine deaminase (ADA) activity were evaluated in pregnant women living with some disease conditions including hypertension, diabetes mellitus and human immunodeficiency virus infection. The subject population is consisted of 15 non-pregnant healthy women [control group (CG)], 15 women with normal pregnancy (NP), 7 women with hypertensive pregnancy (HP), 10 women with gestational diabetes mellitus (GDM) and 12 women with human immunodeficiency virus-infected pregnancy (HIP) groups. The aggregation of platelets was checked using an optical aggregometer, and serum ADA activity was determined using the colorimetric method. After the addition of 5 µM of agonist adenosine diphosphate, the percentage of platelet aggregation was significantly (p < 0·05) increased in NP, HP, GDM and HIP groups when compared with the CG, while the addition of 10 µM of the same agonist caused significant (p < 0·05) elevations in HP, GDM and HIP groups when compared with CG. Furthermore, ADA activity was significantly (p < 0·05) enhanced in NP, HP, GDM and HIP groups when compared with CG. In this study, the increased platelet aggregation and ADA activity in pregnancy and pregnancy-associated diseases suggest that platelet aggregation and ADA activity could serve as peripheral markers for the development of effective therapy in the maintenance of homeostasis and some inflammatory process in these pathophysiological conditions. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

  17. DMSO inhibits human platelet activation through cyclooxygenase-1 inhibition. A novel agent for drug eluting stents?

    Energy Technology Data Exchange (ETDEWEB)

    Asmis, Lars [Institute for Clinical Hematology, University Hospital Zuerich, Zuerich (Switzerland); Tanner, Felix C. [Cardiovascular Research, Physiology Institute, University of Zuerich, Zuerich (Switzerland); Center for Integrative Human Physiology, University of Zuerich, Zuerich (Switzerland); Cardiology, Cardiovascular Center, University Hospital Zuerich, Zuerich (Switzerland); Sudano, Isabella [Cardiology, Cardiovascular Center, University Hospital Zuerich, Zuerich (Switzerland); Luescher, Thomas F. [Cardiovascular Research, Physiology Institute, University of Zuerich, Zuerich (Switzerland); Center for Integrative Human Physiology, University of Zuerich, Zuerich (Switzerland); Cardiology, Cardiovascular Center, University Hospital Zuerich, Zuerich (Switzerland); Camici, Giovanni G., E-mail: giovannic@access.uzh.ch [Cardiovascular Research, Physiology Institute, University of Zuerich, Zuerich (Switzerland); Center for Integrative Human Physiology, University of Zuerich, Zuerich (Switzerland)

    2010-01-22

    Background: DMSO is routinely infused together with hematopoietic cells in patients undergoing myeloablative therapy and was recently found to inhibit smooth muscle cells proliferation and arterial thrombus formation in the mouse by preventing tissue factor (TF), a key activator of the coagulation cascade. This study was designed to investigate whether DMSO prevents platelet activation and thus, whether it may represent an interesting agent to be used on drug eluting stents. Methods and results: Human venous blood from healthy volunteers was collected in citrated tubes and platelet activation was studied by cone and platelet analyzer (CPA) and rapid-platelet-function-assay (RPFA). CPA analysis showed that DMSO-treated platelets exhibit a lower adherence in response to shear stress (-15.54 {+-} 0.9427%, n = 5, P < 0.0001 versus control). Additionally, aggregometry studies revealed that DMSO-treated, arachidonate-stimulated platelets had an increased lag phase (18.0% {+-} 4.031, n = 9, P = 0.0004 versus control) as well as a decreased maximal aggregation (-6.388 {+-} 2.212%, n = 6, P = 0.0162 versus control). Inhibitory action of DMSO could be rescued by exogenous thromboxane A2 and was mediated, at least in part, by COX-1 inhibition. Conclusions: Clinically relevant concentrations of DMSO impair platelet activation by a thromboxane A2-dependent, COX-1-mediated effect. This finding may be crucial for the previously reported anti-thrombotic property displayed by DMSO. Our findings support a role for DMSO as a novel drug to prevent not only proliferation, but also thrombotic complications of drug eluting stents.

  18. Hemocompatibility of Polyvinyl Alcohol-Gelatin Core-Shell Electrospun Nanofibers: A Novel Scaffold for Modulating Platelet Deposition and Activation

    Science.gov (United States)

    Merkle, Valerie M.; Martin, Daniel; Hutchinson, Marcus; Tran, Phat L.; Behrens, Alana; Hossainy, Samir; Bluestein, Danny; Wu, Xiaoyi; Slepian, Marvin J.

    2015-01-01

    In this study, we evaluate coaxial electrospun nanofibers with gelatin in the shell and polyvinyl (PVA) in the core as a potential vascular material by determining fiber surface roughness, as well as human platelet deposition and activation under varying conditions. PVA scaffolds had the highest surface roughness (Ra = 65.5 ± 6.8 nm) but the lowest platelet deposition (34.2 ± 5.8 platelets) in comparison to gelatin nanofibers (Ra = 36.8 ± 3.0 nm & 168.9 ± 29.8 platelets) and coaxial nanofibers (1 Gel: 1 PVA coaxial – Ra = 24.0 ± 1.5 nm & 150.2 ± 17.4 platelets; 3 Gel: 1 PVA coaxial – Ra = 37.1 ± 2.8 nm & 167.8 ± 15.4 platelets). Therefore, the chemical structure of the gelatin nanofibers dominated surface roughness in platelet deposition. Due to their increased stiffness, the coaxial nanofibers had the highest platelet activation rate – rate of thrombin formation, in comparison to gelatin and PVA fibers. Our studies indicate that mechanical stiffness is a dominating factor for platelet deposition and activation, followed by biochemical moieties, and lastly surface roughness. Overall, these coaxial nanofibers are an appealing material for vascular applications by supporting cellular growth while minimizing platelet deposition and activation. PMID:25815434

  19. Argan oil prevents prothrombotic complications by lowering lipid levels and platelet aggregation, enhancing oxidative status in dyslipidemic patients from the area of Rabat (Morocco).

    Science.gov (United States)

    Haimeur, Adil; Messaouri, Hafida; Ulmann, Lionel; Mimouni, Virginie; Masrar, Azelarab; Chraibi, Abdelmjid; Tremblin, Gérard; Meskini, Nadia

    2013-07-20

    It is now established that patients with hyperlipidemia have a high risk of atherosclerosis and thrombotic complications, which are two important events responsible for the onset and progression of cardiovascular disease. In the context of managing dyslipidemia by means of dietary advice based on the consumption of argan oil, we wanted to investigate the effect of virgin argan oil on plasma lipids, and for the first time, on the platelet hyperactivation and oxidative status associated with dyslipidemia. This study concerns patients recruited in the area of Rabat in Morocco. 39 dyslipidemic (79% women) patients were recruited for our study in the area of Rabat in Morocco. They were randomly assigned to the two following groups: the argan group, in which the subjects consumed 25 mL/day of argan oil at breakfast for 3 weeks, and the control group in which argan oil was replaced by butter. After a 3-week consumption period, blood total cholesterol was significantly lower in the argan oil group, as was LDL cholesterol (23.8% and 25.6% lower, respectively). However, the HDL cholesterol level had increased by 26% at the end of the intervention period compared to baseline. Interestingly, in the argan oil group thrombin-induced platelet aggregation was lower, and oxidative status was enhanced as a result of lower platelet MDA and higher GPx activity, respectively. In conclusion, our results, even if it is not representative of the Moroccan population, show that argan oil can prevent the prothrombotic complications associated with dyslipidemia, which are a major risk factor for cardiovascular disease.

  20. Quercetin changes purinergic enzyme activities and oxidative profile in platelets of rats with hypothyroidism.

    Science.gov (United States)

    Baldissarelli, Jucimara; Santi, Adriana; Schmatz, Roberta; Zanini, Daniela; Cardoso, Andréia M; Abadalla, Fátima H; Thomé, Gustavo R; Murussi, Camila; Polachini, Carla R N; Delenogare, Diéssica P; Loro, Vania L; Morsch, Vera M; Schetinger, Maria R C

    2016-12-01

    Diseases related to thyroid hormones have been extensively studied because affect a large number of individuals, and these hormones participate in the regulation of the whole organism homeostasis. However, little is known about the involvement of purinergic signaling related to oxidative stress in hypothyroidism and possible therapeutic adjuncts for treatment of this disorder. Thus, the present study investigates the effects of quercetin on NTPDase, 5'-nucleotidase and adenosine deaminase activities, platelet aggregation and oxidative profile in platelets of rats with methimazole (MMI)-induced hypothyroidism. Methimazole at a concentration of 20mg/100mL was administered for 90days. From the second month the animals received quercetin 10 or 25mg/kg for 60days. Results showed that: Ecto-5'-nucleotidase activity decreased in methimazole/water group and the treatment with quercetin 25mg/kg decreased NTPDase, 5'-nucleotidase and adenosine deaminase activities. Moreover, platelet aggregation increased in methimazole/water group. Lipid peroxidation increased while superoxide dismutase and catalase activities decreased, but, interestingly, the treatment with quercetin reversed these changes. These results demonstrated that quercetin modulates adenine nucleotide hydrolysis decreasing the ADP formation and adenosine deamination. At the same time quercetin improves the oxidative profile, as well as reduces platelet aggregation, which together with the modulation in the nucleotides levels can contribute to the prevention of platelet disorders.

  1. Differential procoagulant activity of microparticles derived from monocytes, granulocytes, platelets and endothelial cells: impact of active tissue factor.

    Science.gov (United States)

    Shustova, Olga N; Antonova, Olga A; Golubeva, Nina V; Khaspekova, Svetlana G; Yakushkin, Vladimir V; Aksuk, Svetlana A; Alchinova, Irina B; Karganov, Mikhail Y; Mazurov, Alexey V

    2016-12-06

    Microparticles released by activated/apoptotic cells exhibit coagulation activity as they express phosphatidylserine and some of them - tissue factor. We compared procoagulant properties of microparticles from monocytes, granulocytes, platelets and endothelial cells and assessed the impact of tissue factor in observed differences. Microparticles were sedimented (20 000g, 30 min) from the supernatants of activated monocytes, monocytic THP-1 cells, granulocytes, platelets and endothelial cells. Coagulation activity of microparticles was examined using plasma recalcification assay. The size of microparticles was evaluated by dynamic light scattering. Tissue factor activity was measured by its ability to activate factor X. All microparticles significantly accelerated plasma coagulation with the shortest lag times for microparticles derived from monocytes, intermediate - for microparticles from THP-1 cells and endothelial cells, and the longest - for microparticles from granulocytes and platelets. Average diameters of microparticles ranged within 400-600 nm. The largest microparticles were produced by endothelial cells and granulocytes, smaller - by monocytes, and the smallest - by THP-1 cells and platelets. The highest tissue factor activity was detected in microparticles from monocytes, lower activity - in microparticles from endothelial cells and THP-1 cells, and no activity - in microparticles from platelets and granulocytes. Anti-tissue factor antibodies extended coagulation lag times for microparticles from monocytes, endothelial cells and THP-1 cells and equalized them with those for microparticles from platelets and granulocytes. Higher coagulation activity of microparticles from monocytes, THP-1 cells and endothelial cells in comparison with microparticles from platelets and granulocytes is determined mainly by the presence of active tissue factor.

  2. Exogenous L-arginine and HDL can alter LDL and ox-LDL-mediated platelet activation: using platelet P-selectin receptor numbers.

    Science.gov (United States)

    Sener, Azize; Enc, Elif; Ozsavci, Derya; Vanizor-Kural, Birgul; Yanikkaya-Demirel, Gulderen; Oba, Rabia; Uras, Fikriye; Demir, Muzaffer

    2011-01-01

    The aim of this study is to investigate the effects of exogenous L-arginine and HDL on LDL and oxidized LDL (ox-LDL)-mediated platelet activation. Adenosine diphosphate (ADP)-activated platelets have been incubated with lipoproteins with or without L-arginine. P-selectin receptor numbers per platelet have been measured by flow cytometry. After incubation with only L-arginine (without lipoproteins), platelet nitric oxide (NO) levels and P-selectin receptor numbers significantly increased compared to the controls (P LDL or ox-LDL, receptor numbers of P-selectin significantly increased (P LDL or L-arginine + ox-LDL decreased compared to the levels in platelets treated with only LDL or ox-LDL (P HDL to L-arginine + ox-LDL caused significant reduction in P-selectin receptor numbers as in the control values (P LDL or ox-LDL on platelet P-selectin receptor numbers and HDL also strengthens this effect of L-arginine.

  3. The GPIIb/IIIa antagonist eptifibatide markedly potentiates platelet-leukocyte interaction and tissue factor expression following platelet activation in whole blood in vitro.

    Science.gov (United States)

    Scholz, Thomas; Zhao, Lian; Temmler, Uta; Bath, Philip; Heptinstall, Stan; Lösche, Wolfgang

    2002-11-01

    Tissue factor (TF) is the most important initiator of intravascular coagulation. Activated platelets are able to adhere to leukocytes and this heterotypic cell-cell interaction results in a CD62P-dependent TF expression on monocytes. GPIIb/IIIa antagonists are inhibitors of the common pathway of platelet aggregation and they are widely used in patients with acute coronary syndromes undergoing coronary interventions. As GPIIb/IIIa antagonists do not prevent platelet activation we investigated the effect a GPIIb/IIIa antagonist, eptifibatide, on the formation of platelet-leukocyte conjugates and leukocyte TF expression. Flow cytometry was used to detect conjugates and TF. When platelets in citrated human blood were stimulated for 30 min with collagen there was a increase in the number of both neutrophils and monocytes with the platelet-specific antigen CD42a, indicating the formation of platelet-neutrophil (P/N) and platelet-monocyte (P/M) conjugates. P/M formation was associated with about a 2.5-fold increase in TF expression on monocytes, whereas P/N formation changed TF expression neutrophils only by about 10%. Eptifibatide enhanced dose-dependently (0.0625-1.5 microg/ml) both collagen-induced P/M formation and monocyte TF expression. Maximum enhancement by about 60 and 120%, respectively, was observed at 0.5 microg/ml eptifibatide. In contrast, eptifibatide had only a minor effect on P/N formation and no effect on neutrophil TF expression. The augmented P/M formation and monocyte TF expression in the presence of a GPIIb/IIIa antagonist may be relevant to the poor antithrombotic efficiency of oral GPIIb/IIIa antagonists as shown in recent large clinical trials.

  4. Lymphocyte-mediated regulation of platelet activation during desensitization in patients with hymenoptera venom hypersensitivity.

    Science.gov (United States)

    Ledru, E; Pestel, J; Tsicopoulos, A; Joseph, M; Wallaert, B; Tonnel, A B; Capron, A

    1988-01-01

    T cells from peripheral blood of hymenoptera sensitive patients were studied before and after venom desensitization. Before treatment, T cells showed a variable but higher proliferative response to allergen than T cells of treated patients or controls. While before desensitization, T cell products, specifically released after in vitro allergen stimulation, were able to amplify the IgE-dependent platelet activity, we showed that after treatment of the same patients, T cell products strongly reduced platelet activation. Considering the modifications in platelet activation previously observed in patients treated by specific immunotherapy, the present results suggest that, through a modification of T cell reactivity to allergen, T cell functions are modulated by desensitization, and emphasize the involvement of T cell products in the desensitization mechanisms. PMID:3263227

  5. Evaluation of the antibacterial activity and biocompatibility for silver nanoparticles immobilized on nano silicate platelets.

    Science.gov (United States)

    Lin, Jiang-Jen; Lin, Wen-Chun; Li, Shing-Da; Lin, Cheng-Yen; Hsu, Shan-hui

    2013-01-23

    Silver nanoparticles (AgNPs) are known for their bactericidal abilities. The antibacterial potency is dependent on the particle size and dispersion status. In this study, we synthesized AgNP/NSP nanohybrids in two different weight ratios (1/99 and 8/92) using the fully exfoliated clay, i.e., nanosilicate platelets (NSP), as a dispersing agent and carrier for AgNPs. Due to the size of NSP, the immobilized AgNPs do not enter cells readily, which may lower the risk associated with the cellular uptake of AgNPs. The biocompatibility, immunological response, and antimicrobial activities of AgNP/NSP hybrids were evaluated. The results revealed that AgNP/NSP hybrids elicited merely mild inflammatory response and retained the outstanding antibacterial activity. The hybrids were further embedded in poly(ether)urethane (PEU) to increase the biocompatibility. At the same silver content (20 ppm), the PEU-AgNP/NSP nanocomposites were nontoxic to mouse skin fibroblasts, while simultaneously exhibiting nearly complete bacterial growth reduction (99.9%). PEU containing the same amount of free AgNPs did not display such an effect. Our results verify the better biosafety of the AgNPs/NSP hybrids and their polymer nanocomposites for further clinical use.

  6. Statins have beneficial effects on platelet free radical activity and intracellular distribution of GTPases in hyperlipidaemia.

    Science.gov (United States)

    Hamilton, Paul K; Hughes, Sinead M T; Plumb, Richard D; Devine, Adrian; Leahey, William; Lyons, Kristopher S; Johnston, Dennis; McVeigh, Gary E

    2010-03-01

    In addition to lowering cholesterol, statins may alter endothelial release of the vasodilator NO and harmful superoxide free radicals. Statins also reduce cholesterol intermediates including isoprenoids. These are important for post-translational modification of substances including the GTPases Rho and Rac. By altering the membrane association of these molecules, statins affect intracellular positioning and hence activity of a multitude of substances. These include eNOS(endothelial NO synthase), which produces NO (inhibited by Rho), and NADPH oxidase, which produces superoxide (dependent on Rac). Statins may improve endothelial function by enhancing production of NO while decreasing superoxide production. A total of 40 hypercholesterolaemic patients were randomized to treatment with either atorvastatin or placebo; 20 normolipidaemic patients were also studied. Platelet nitrite, NO and superoxide were examined as was the cellular distribution of the GTPases Rho and Rac at baseline and after 8 weeks of treatment.Following atorvastatin therapy, platelet NO was increased (3.2 pmol/10(8) platelets) and superoxide output was attenuated [-3.4 pmol min(-1) (10(8) platelets)(-1)] when compared with placebo. The detection of both Rho and Rac was significantly reduced in the membranes of platelets, implying reduced activity. In conclusion, the results of the present study show altered NO/superoxide production following statin therapy. A potential mechanism for this is the change in the distribution of intracellular GTPases, which was considered to be secondary to decreases in isoprenoid intermediates, suggesting that the activity of the former had been affected by atorvastatin.

  7. Secretory phospholipase A2 modified HDL rapidly and potently suppresses platelet activation.

    Science.gov (United States)

    Curcic, Sanja; Holzer, Michael; Pasterk, Lisa; Knuplez, Eva; Eichmann, Thomas O; Frank, Saša; Zimmermann, Robert; Schicho, Rudolf; Heinemann, Akos; Marsche, Gunther

    2017-08-14

    Levels of secretory phospholipases A2 (sPLA2) highly increase under acute and chronic inflammatory conditions. sPLA2 is mainly associated with high-density lipoproteins (HDL) and generates bioactive lysophospholipids implicated in acute and chronic inflammatory processes. Unexpectedly, pharmacological inhibition of sPLA2 in patients with acute coronary syndrome was associated with an increased risk of myocardial infarction and stroke. Given that platelets are key players in thrombosis and inflammation, we hypothesized that sPLA2-induced hydrolysis of HDL-associated phospholipids (sPLA2-HDL) generates modified HDL particles that affect platelet function. We observed that sPLA2-HDL potently and rapidly inhibited platelet aggregation induced by several agonists, P-selectin expression, GPIIb/IIIa activation and superoxide production, whereas native HDL showed little effects. sPLA2-HDL suppressed the agonist-induced rise of intracellular Ca(2+) levels and phosphorylation of Akt and ERK1/2, which trigger key steps in promoting platelet activation. Importantly, sPLA2 in the absence of HDL showed no effects, whereas enrichment of HDL with lysophosphatidylcholines containing saturated fatty acids (the main sPLA2 products) mimicked sPLA2-HDL activities. Our findings suggest that sPLA2 generates lysophosphatidylcholine-enriched HDL particles that modulate platelet function under inflammatory conditions.

  8. Protein disulfide isomerase inhibition blocks thrombin generation in humans by interfering with platelet factor V activation

    Science.gov (United States)

    Stopa, Jack D.; Neuberg, Donna; Puligandla, Maneka; Furie, Bruce; Zwicker, Jeffrey I.

    2017-01-01

    BACKGROUND: Protein disulfide isomerase (PDI) is required for thrombus formation. We previously demonstrated that glycosylated quercetin flavonoids such as isoquercetin inhibit PDI activity and thrombus formation in animal models, but whether extracellular PDI represents a viable anticoagulant target in humans and how its inhibition affects blood coagulation remain unknown. METHODS: We evaluated effects of oral administration of isoquercetin on platelet-dependent thrombin generation in healthy subjects and patients with persistently elevated anti-phospholipid antibodies. RESULTS: Following oral administration of 1,000 mg isoquercetin to healthy adults, the measured peak plasma quercetin concentration (9.2 μM) exceeded its IC50 for inhibition of PDI by isoquercetin in vitro (2.5 ± 0.4 μM). Platelet-dependent thrombin generation decreased by 51% in the healthy volunteers compared with baseline (P = 0.0004) and by 64% in the anti-phospholipid antibody cohort (P = 0.015) following isoquercetin ingestion. To understand how PDI affects thrombin generation, we evaluated substrates of PDI identified using an unbiased mechanistic-based substrate trapping approach. These studies identified platelet factor V as a PDI substrate. Isoquercetin blocked both platelet factor Va and thrombin generation with an IC50 of ~5 μM. Inhibition of PDI by isoquercetin ingestion resulted in a 53% decrease in the generation of platelet factor Va (P = 0.001). Isoquercetin-mediated inhibition was reversed with addition of exogenous factor Va. CONCLUSION: These studies show that oral administration of isoquercetin inhibits PDI activity in plasma and diminishes platelet-dependent thrombin generation predominantly by blocking the generation of platelet factor Va. These pharmacodynamic and mechanistic observations represent an important step in the development of a novel class of antithrombotic agents targeting PDI. TRIAL REGISTRATION: Clinicaltrials.gov (NCT01722669) FUNDING: National Heart

  9. Effect of exercise on platelet activation during aspirin or clopidogrel intake in healthy men

    DEFF Research Database (Denmark)

    Hjorth Madsen, Esben; Christiansen, Morten Krogh; Schmidt, Erik Berg;

    2009-01-01

    aggregometry. A significant increase in plasma von Willebrand Factor was also found in response to exercise. In conclusion, platelet activation occurs during exercise in healthy individuals. This activation is not prevented by use of aspirin or clopidogrel, and may partly be explained by an increase in plasma...

  10. Platelet-activating factor acetylhydrolase and haemophagocytosis in the sepsis syndrome

    Directory of Open Access Journals (Sweden)

    Franck Trimoreau

    2000-01-01

    Full Text Available Sepsis syndrome (SS is associated with depressed PAF acetylhydrolase, the enzyme responsible for the degradation of platelet activating factor. PAF acetylhydrolase is in a large part produced by macrophages, whose inadequate activation with haemophagocytosis is frequent in patients with SS.

  11. Effects of Anti-CD59 on Complement- induced Platelet Activation in Adult Males with Coronary Heart Disease

    Institute of Scientific and Technical Information of China (English)

    王礼春; 马虹; 黄守坚; 麦炜颐; 董吁钢; 曾武涛; 廖新学; 何建桂; 徐冬

    2003-01-01

    Objectives To study the reactions of platelet to active complement and the ef-fects of anti- CD59 on platelet activation induced bycomplement in coronary heart disease (CHD) adultmales. Methods By applying cobra venom factor(CVF) to activate complement, observed the plateletaggregation and release reactions induced by activecomplement with or without applying anti- CD59 toblock the complement modulation protein CD59.Results CVF could induce platelet of CHD individ-uals release ATP and cause significant and lastingmetamorphosis, but failed to induce platelet aggregate.The platelet maximum shape change showed positivelinear correlation with lg concentration of CVF. Theregressive equation was Y=28.7171gx - 19. 798 ( r =0. 956, P <0.01, n = 36). Anti - CD59 could enhanceCVF- induced platelet shape change and ATP releasewith a dose-dependent manner. ConclusionsComplement activated by CVF can induce significantand lasting platelet metamorphosis and release reac-tion, but can't induce platelet aggregation in CHD adultmales. Anti -CD59 can promote the platelet reactionsinduced by active complement.

  12. Synthesis of huaicarbon A/B and their activating effects on platelet glycoprotein VI receptor to mediate collagen-induced platelet aggregation

    Science.gov (United States)

    Yu, Hongli; Chen, Yeqing; Wu, Hao; Wang, Kuilong; Liu, Liping; Zhang, Xingde

    2017-01-01

    Quercetin and rhamnose were efficiently converted into huaicarbon A/B by heating at 250°C for 10-15 min or at 200°C for 25-30 min. With the optimum molar ratio of quercetin/rhamnose (1:3), huaicarbon A and B yields reached 25% and 16% respectively after heating at 250°C, with 55% quercetin conversion. Huaicarbon A/B both promoted washed platelet aggregation dose-dependently, which was antagonized by an inhibitor of glycoprotein VI (GPVI) receptor. Similarly, they both promoted collagen-induced platelet aggregation in platelet-rich plasma in dose-dependent manners. According to the S type dose-response model, EC50 values of huaicarbon A and huaicarbon B were calculated as 33.48 μM and 48.73 μM respectively. They induced intracellular Ca2+ accumulation that was specifically blocked by GPVI antagonist. Huaicarbon A/B enhanced intracellular Ca2+ accumulation and facilitated collagen-induced platelet aggregation, which were blocked by GPVI antagonist. They were conducive to collagen-induced platelet aggregation by activating platelet GPVI receptor. PMID:28337278

  13. Ultraviolet-B irradiation of platelets induces a dose-dependent increase in the expression of platelet activation markers with storage

    Energy Technology Data Exchange (ETDEWEB)

    Grijzenhout, M.A. (University Hospital, Utrecht (Netherlands) National Inst. of Public Health Care and Environmental Hygiene, Bilthoven (Netherlands)); Aarts-Rimens, M.I.; Akkerman, J.W.N.; Nieuwenhuis, H.K.; Weelden, H. van; Prooijen, H.C. van (University Hospital, Utrecht (Netherlands))

    1993-04-01

    Ultraviolet B (UVB) irradiation of platelet concentrates (PCs) has been proposed as a novel technology to prevent HLA sensitization. In order to increase the efficacy of UV irradiation for the prevention of HLA sensitization, the authors exposed PCs to 4 or 8 J/cm[sup 2] of UVB and evaluated the effect of UV radiation on platelet integrity during storage. They report here that UV exposed platelets show a progressive increase in the expression of activation markers P-selectin (GMP-140; CD62) and LIMP-CD63 (GP-53; CD63) on the platelet membrane over time in a dose-dependent manner compared to age-matched controls. Platelet metabolism was also enhanced as evidenced by significant changes in lactate and pH during post-irradiation storage. Based on these findings we transfused PCs within 4 h after UV irradiation. PCs exposed to 4 J/cm[sup 2] showed normal post-transfusion recoveries haemostatic functions, while poor platelet recoveries were found after administration of PCs exposed to 8 J/cm[sup 2]. (author).

  14. Early local intracoronary platelet activation after drug-eluting stent placement

    Institute of Scientific and Technical Information of China (English)

    Ailiman Mahemuti; Nicolas Meneveau; Marie-France Seronde; Francois Schiele; Mariette Mercier; Evelyne Racadot; Jean-Pierre Bassand

    2007-01-01

    Background Early local platelet activation after coronary intervention identifies patients at increased risk of acute stent thrombosis (AST). However, early changes in platelet activation in coronary circulation following drug-eluting stent (DES) implantation have never been reported.Methods In a prospective study of 26 consecutive elective stable angina patients, platelet activation was analyzed by measuring soluble glycoprotein V (sGPV) and P-selectin (CD62P) before and after implantation of either DES or bare metal stent (BMS). All patients were pretreated with clopidogrel (300 mg loading dose) and aspirin (75 mg orally) the day before the procedure. Blood samples were drawn from the coronary ostium and 10 - 20 mm distal to the lesion site.Results Consistent with the lower baseline clinical risk, the levels of CD62P and sGPV were within normal reference range, both in the coronary ostium and distal to the lesion before percutaneous coronary intervention (PCl) procedure.The levels of CD62P and sGPV did not change significantly (CD62P: (31.1 ± 9.86) ng/ml vs (29.5 ± 9.02) ng/ml, P=0.319and sGPV: (52.4 ± 13.5) ng/ml vs (51.8 ± 11.7) ng/ml, P=0.674, respectively) after stent implantation when compared with baseline. Changes in these platelet activation markers did not differ between stent types.Conclusions Intracoronary local platelet activation does not occur in stable angina patients before and immediately following DES implantation when dual anti-platelet is administered.

  15. Melanoma cell metastasis via P-selectin-mediated activation of acid sphingomyelinase in platelets.

    Science.gov (United States)

    Becker, Katrin Anne; Beckmann, Nadine; Adams, Constantin; Hessler, Gabriele; Kramer, Melanie; Gulbins, Erich; Carpinteiro, Alexander

    2017-01-01

    Metastatic dissemination of cancer cells is one of the hallmarks of malignancy and accounts for approximately 90 % of human cancer deaths. Within the blood vasculature, tumor cells may aggregate with platelets to form clots, adhere to and spread onto endothelial cells, and finally extravasate to form metastatic colonies. We have previously shown that sphingolipids play a central role in the interaction of tumor cells with platelets; this interaction is a prerequisite for hematogenous tumor metastasis in at least some tumor models. Here we show that the interaction between melanoma cells and platelets results in rapid and transient activation and secretion of acid sphingomyelinase (Asm) in WT but not in P-selectin-deficient platelets. Stimulation of P-selectin resulted in activation of p38 MAPK, and inhibition of p38 MAPK in platelets prevented the secretion of Asm after interaction with tumor cells. Intravenous injection of melanoma cells into WT mice resulted in multiple lung metastases, while in P-selectin-deficient mice pulmonary tumor metastasis and trapping of tumor cells in the lung was significantly reduced. Pre-incubation of tumor cells with recombinant ASM restored trapping of B16F10 melanoma cells in the lung in P-selectin-deficient mice. These findings indicate a novel pathway in tumor metastasis, i.e., tumor cell mediated activation of P-selectin in platelets, followed by activation and secretion of Asm and in turn release of ceramide and tumor metastasis. The data suggest that p38 MAPK acts downstream from P-selectin and is necessary for the secretion of Asm.

  16. Human Platelets Utilize Cycloxygenase-1 to Generate Dioxolane A3, a Neutrophil-activating Eicosanoid.

    Science.gov (United States)

    Hinz, Christine; Aldrovandi, Maceler; Uhlson, Charis; Marnett, Lawrence J; Longhurst, Hilary J; Warner, Timothy D; Alam, Saydul; Slatter, David A; Lauder, Sarah N; Allen-Redpath, Keith; Collins, Peter W; Murphy, Robert C; Thomas, Christopher P; O'Donnell, Valerie B

    2016-06-24

    Eicosanoids are important mediators of fever, pain, and inflammation that modulate cell signaling during acute and chronic disease. We show by using lipidomics that thrombin-activated human platelets generate a new type of eicosanoid that both stimulates and primes human neutrophil integrin (Mac-1) expression, in response to formylmethionylleucylphenylalanine. Detailed characterization proposes a dioxolane structure, 8-hydroxy-9,11-dioxolane eicosatetraenoic acid (dioxolane A3, DXA3). The lipid is generated in nanogram amounts by platelets from endogenous arachidonate during physiological activation, with inhibition by aspirin in vitro or in vivo, implicating cyclooxygenase-1 (COX). Pharmacological and genetic studies on human/murine platelets revealed that DXA3 formation requires protease-activated receptors 1 and 4, cytosolic phospholipase A2 (cPLA2), Src tyrosine kinases, p38 MAPK, phospholipase C, and intracellular calcium. From data generated by purified COX isoforms and chemical oxidation, we propose that DXA3 is generated by release of an intermediate from the active site followed by oxygenation at C8. In summary, a new neutrophil-activating platelet-derived lipid generated by COX-1 is presented that can activate or prime human neutrophils, suggesting a role in innate immunity and acute inflammation.

  17. Human Platelets Utilize Cycloxygenase-1 to Generate Dioxolane A3, a Neutrophil-activating Eicosanoid*

    Science.gov (United States)

    Hinz, Christine; Aldrovandi, Maceler; Uhlson, Charis; Marnett, Lawrence J.; Longhurst, Hilary J.; Warner, Timothy D.; Alam, Saydul; Slatter, David A.; Lauder, Sarah N.; Allen-Redpath, Keith; Collins, Peter W.; Murphy, Robert C.; Thomas, Christopher P.; O'Donnell, Valerie B.

    2016-01-01

    Eicosanoids are important mediators of fever, pain, and inflammation that modulate cell signaling during acute and chronic disease. We show by using lipidomics that thrombin-activated human platelets generate a new type of eicosanoid that both stimulates and primes human neutrophil integrin (Mac-1) expression, in response to formylmethionylleucylphenylalanine. Detailed characterization proposes a dioxolane structure, 8-hydroxy-9,11-dioxolane eicosatetraenoic acid (dioxolane A3, DXA3). The lipid is generated in nanogram amounts by platelets from endogenous arachidonate during physiological activation, with inhibition by aspirin in vitro or in vivo, implicating cyclooxygenase-1 (COX). Pharmacological and genetic studies on human/murine platelets revealed that DXA3 formation requires protease-activated receptors 1 and 4, cytosolic phospholipase A2 (cPLA2), Src tyrosine kinases, p38 MAPK, phospholipase C, and intracellular calcium. From data generated by purified COX isoforms and chemical oxidation, we propose that DXA3 is generated by release of an intermediate from the active site followed by oxygenation at C8. In summary, a new neutrophil-activating platelet-derived lipid generated by COX-1 is presented that can activate or prime human neutrophils, suggesting a role in innate immunity and acute inflammation. PMID:27129261

  18. Effects of antiplatelet therapy on platelet extracellular vesicle release and procoagulant activity in health and in cardiovascular disease.

    Science.gov (United States)

    Connor, David E; Ly, Ken; Aslam, Anoosha; Boland, John; Low, Joyce; Jarvis, Susan; Muller, David W; Joseph, Joanne E

    2016-12-01

    Dual antiplatelet therapy with aspirin and clopidogrel is commonly used to prevent recurrent ischemic events in patients with cardiovascular disease. Whilst their effects on platelet reactivity are well documented, it is unclear, however, whether antiplatelet therapy inhibits platelet extracellular vesicle (EV) release. The aim of this study was to investigate the effects of antiplatelet therapy on platelet EV formation and procoagulant activity. Blood samples from 10 healthy controls not receiving antiplatelet therapy were incubated in vitro with aspirin or a P2Y12 inhibitor (MeSAMP). Blood samples from 50 patients receiving long-term dual antiplatelet therapy and undergoing coronary angiography were also studied. Platelet reactivity was assessed by Multiplate™ impedance aggregometry. Platelet EV formation and procoagulant activity of pretreated and untreated blood samples in response to arachidonic acid (AA), adenosine diphosphate (ADP), ADP+PGE1, and thrombin receptor-activating peptide (TRAP) stimulation were assessed by flow cytometry and Procoag-PL assays, respectively. Incubation of normal platelets with aspirin significantly inhibited AA-induced platelet reactivity, EV formation, and procoagulant activity, whilst MeSAMP significantly inhibited platelet reactivity and EV formation in response to AA, ADP, and TRAP, but had minimal effect on procoagulant activity. Most patients receiving dual antiplatelet therapy showed an appropriate reduction in platelet reactivity in response to their treatment; however there was not complete inhibition of increased platelet and EV procoagulant activity in response to ADP, AA, or TRAP. In addition, we could not find any correlation between platelet reactivity and procoagulant activity in patients receiving dual antiplatelet therapy.

  19. Contribution of chondroitin sulfate A to the binding of complement proteins to activated platelets.

    Directory of Open Access Journals (Sweden)

    Osama A Hamad

    Full Text Available BACKGROUND: Exposure of chondroitin sulfate A (CS-A on the surface of activated platelets is well established. The aim of the present study was to investigate to what extent CS-A contributes to the binding of the complement recognition molecule C1q and the complement regulators C1 inhibitor (C1INH, C4b-binding protein (C4BP, and factor H to platelets. PRINCIPAL FINDINGS: Human blood serum was passed over Sepharose conjugated with CS-A, and CS-A-specific binding proteins were identified by Western blotting and mass spectrometric analysis. C1q was shown to be the main protein that specifically bound to CS-A, but C4BP and factor H were also shown to interact. Binding of C1INH was dependent of the presence of C1q and then not bound to CS-A from C1q-depleted serum. The specific interactions observed of these proteins with CS-A were subsequently confirmed by surface plasmon resonance analysis using purified proteins. Importantly, C1q, C4BP, and factor H were also shown to bind to activated platelets and this interaction was inhibited by a CS-A-specific monoclonal antibody, thereby linking the binding of C1q, C4BP, and factor H to exposure of CS-A on activated platelets. CS-A-bound C1q was also shown to amplify the binding of model immune complexes to both microtiter plate-bound CS-A and to activated platelets. CONCLUSIONS: This study supports the concept that CS-A contributes to the binding of C1q, C4BP, and factor H to platelets, thereby adding CS-A to the previously reported binding sites for these proteins on the platelet surface. CS-A-bound C1q also seems to amplify the binding of immune complexes to activated platelets, suggesting a role for this molecule in immune complex diseases.

  20. Sepsis prediction in critically ill patients by platelet activation markers on ICU admission: a prospective pilot study.

    Science.gov (United States)

    Layios, Nathalie; Delierneux, Céline; Hego, Alexandre; Huart, Justine; Gosset, Christian; Lecut, Christelle; Maes, Nathalie; Geurts, Pierre; Joly, Arnaud; Lancellotti, Patrizio; Albert, Adelin; Damas, Pierre; Gothot, André; Oury, Cécile

    2017-12-01

    Platelets have been involved in both immune surveillance and host defense against severe infection. To date, whether platelet phenotype or other hemostasis components could be associated with predisposition to sepsis in critical illness remains unknown. The aim of this work was to identify platelet markers that could predict sepsis occurrence in critically ill injured patients. This single-center, prospective, observational, 7-month study was based on a cohort of 99 non-infected adult patients admitted to ICUs for elective cardiac surgery, trauma, acute brain injury, and post-operative prolonged ventilation and followed up during ICU stay. Clinical characteristics and severity score (SOFA) were recorded on admission. Platelet activation markers, including fibrinogen binding to platelets, platelet membrane P-selectin expression, plasma soluble CD40L, and platelet-leukocytes aggregates were assayed by flow cytometry at admission and 48 h later, and then at the time of sepsis diagnosis (Sepsis-3 criteria) and 7 days later for sepsis patients. Hospitalization data and outcomes were also recorded. Of the 99 patients, 19 developed sepsis after a median time of 5 days. These patients had a higher SOFA score at admission; levels of fibrinogen binding to platelets (platelet-Fg) and of D-dimers were also significantly increased compared to the other patients. Levels 48 h after ICU admission no longer differed between the two patient groups. Platelet-Fg % was an independent predictor of sepsis (P = 0.0031). By ROC curve analysis, cutoff point for Platelet-Fg (AUC = 0.75) was 50%. In patients with a SOFA cutoff of 8, the risk of sepsis reached 87% when Platelet-Fg levels were above 50%. Patients with sepsis had longer ICU and hospital stays and higher death rate. Platelet-bound fibrinogen levels assayed by flow cytometry within 24 h of ICU admission help identifying critically ill patients at risk of developing sepsis.

  1. Iron deficiency generates secondary thrombocytosis and platelet activation in IBD: the randomized, controlled thromboVIT trial.

    Science.gov (United States)

    Kulnigg-Dabsch, Stefanie; Schmid, Werner; Howaldt, Stefanie; Stein, Jürgen; Mickisch, Oliver; Waldhör, Thomas; Evstatiev, Rayko; Kamali, Houman; Volf, Ivo; Gasche, Christoph

    2013-07-01

    Secondary thrombocytosis is a common clinical feature. In patients with cancer, it is a risk factor for venous thromboembolic events. In inflammatory bowel disease (IBD), thrombocytosis is so far considered a marker of active disease and may contribute to the increased thromboembolic risk in this population. Observed effects of iron therapy on normalization of platelet counts led us to hypothesize that iron itself may regulate megakaryopoiesis. Here, we want to test the effect of iron replacement on platelet count and activity in IBD-associated thrombocytosis. We performed a randomized, single-blinded placebo-controlled trial testing the effect of ferric carboxymaltose (FCM) in patients with IBD with secondary thrombocytosis (platelets > 450 G/L). Changes in platelet counts, hemoglobin, iron parameters, disease activity, megakaryopoietic growth factors, erythropoietin, and platelet activity were assessed. Patients received placebo or up to 1500 mg iron as FCM. Endpoints were evaluated at week 6. A total of 26 patients were included in the study, 15 patients were available for the per protocol analysis. A drop in platelets >25% (primary endpoint) was observed in 4 of 8 (50%, iron group) and 1 of 7 patients (14%, placebo group, P = 0.143). Mean platelet counts dropped on FCM but not on placebo (536 G/L to 411 G/L versus 580 G/L to 559 G/L; P = 0.002). Disease activity and megakaryopoietic growth factors remained unchanged and hemoglobin and iron parameters increased on FCM. The normalization of platelet counts was associated with a decrease in platelet aggregation and P-selectin expression. FCM lowers platelet counts and platelet activation in patients with IBD-associated secondary thrombocytosis.

  2. Enhanced retention of in vitro functional activity of platelets from recombinant human thrombopoietin-treated patients following long-term cryopreservation with a platelet-preserving solution (ThromboSol) and 2% DMSO.

    Science.gov (United States)

    Vadhan-Raj, S; Currie, L M; Bueso-Ramos, C; Livesey, S A; Connor, J

    1999-02-01

    Chemotherapy-induced thrombocytopenia represents a significant clinical problem in the management of patients with malignancy. Recombinant human thrombopoietin (rhTPO) is a potent stimulator of platelet production in vivo. The ability to cryopreserve rhTPO-derived platelets would enable the use of autologous platelets during the period of thrombocytopenia. ThromboSol is a platelet-stabilizing formulation consisting of second messenger effectors that inhibit specific activation pathways endogenous to platelets. To investigate the effect of ThromboSol cryopreservation, platelets from rhTPO-treated patients (n = 23) and normal donors were treated with ThromboSol and 2% DMSO and cryopreserved for up to 6 months. The platelets were thawed at different intervals and tested for retention of platelet functional activity in vitro. Following a short-term storage (1 week), the cryopreserved platelets from patients treated with rhTPO exhibited significantly higher retention of functional activities including discoid morphology (70% v 57%), extent of shape change (19% v 13%) stirring shape change (15% v 11%) and hypotonic shock response (56% v 25%), as compared to the cryopreserved platelets from controls. Furthermore, there was no further significant loss of functional activity following cryopreservation for up to 6 months. These findings suggest that cryopreservation of platelets from rhTPO-treated donors may provide a useful novel strategy for autologous or allogeneic donation for subsequent transfusions to manage treatment-related thrombocytopenia.

  3. Perbedaan Kadar Platelet Activating Factor Plasma antara Penderita Demam Berdarah Dengue dan Demam Dengue

    Directory of Open Access Journals (Sweden)

    Djatnika Setiabudi

    2013-12-01

    Full Text Available Dengue virus infection can manifest as dengue fever and, more severely, as dengue hemorrhagic fever. Their pathogenesis until now is not fully understood. One of the most favorable theories stated the presence of increasing titer of pro-inflammatory mediator in severe dengue. The aim of this study was to determine the difference of plasma platelet activating factor titer between dengue hemorrhagic fever and dengue fever patients. This observational study with cross sectional design was conducted during January–February 2013. Subjects were dengue patients, 1 to 14 years old, hospitalized at Dr. Hasan Sadikin General Hospital, Bandung District Hospital (Ujungberung, and Cimahi District Hospital (Cibabat. Dengue cases were confirmed based on nonstructural-1 antigen and/or immunoglobulin M and G rapid test. Blood samples from febrile, critical and recovery phase were drawn for the examination of platelet activating factor titer using the enzyme-linked immunosorbent assay method. There were 26 dengue cases (14 as dengue fever and 12 as dengue hemorrhagic fever. Plasma platelet activating factor titer at the critical phase was significantly higher in dengue hemorrhagic fever patients [541.45 (239.30–2,449.00] pg/mL compared to dengue fever patients [289.55 (149.50–961.50] pg/mL; p=0.007. In conclusion, plasma platelet activating factor titer at the critical phase is higher in dengue hemorrhagic fever patients than in dengue fever patients.

  4. Study on the relationship between serum interleukins, platelet activation indexes and cerebral infarction

    Institute of Scientific and Technical Information of China (English)

    Bo Wu

    2015-01-01

    Objective:To study and investigate the relationship between serum interleukins, platelet activation indexes and cerebral infarction.Methods:58 patients with cerebral infarction in our hospital from March 2013 to September 2014 were selected as observation group; meanwhile, 58 healthy persons at the same period were selected as control group, then the serum interleukins and platelet activation indexes of two groups were detected and compared, then the detection results of observation group with different stages and severity of cerebral infarction were compared too, and the relationship between those blood detection indexes and cerebral infarction were analyzed by the Logistic analysis.Results:The serum interleukins and platelet activation indexes of observation group were obviously higher than those of control group, and the detection levels of observation group with cerebral infarction at early and severe stage were obviously higher than those of patients at other stages and light, moderate, and those blood indexes all had close relationship to the cerebral infarction by the Logistic analysis,P<0.05. Conclusion:The serum interleukins and platelet activation indexes all have close relationship to cerebral infarction, and they can be as the important monitoring indexes of the disease.

  5. Three-dimentional simulation of flow-induced platelet activation in artificial heart valves

    Science.gov (United States)

    Hedayat, Mohammadali; Asgharzadeh, Hafez; Borazjani, Iman

    2015-11-01

    Since the advent of heart valve, several valve types such as mechanical and bio-prosthetic valves have been designed. Mechanical Heart Valves (MHV) are durable but suffer from thromboembolic complications that caused by shear-induced platelet activation near the valve region. Bio-prosthetic Heart Valves (BHV) are known for better hemodynamics. However, they usually have a short average life time. Realistic simulations of heart valves in combination with platelet activation models can lead to a better understanding of the potential risk of thrombus formation in such devices. In this study, an Eulerian approach is developed to calculate the platelet activation in three-dimensional simulations of flow through MHV and BHV using a parallel overset-curvilinear immersed boundary technique. A curvilinear body-fitted grid is used for the flow simulation through the anatomic aorta, while the sharp-interface immersed boundary method is used for simulation of the Left Ventricle (LV) with prescribed motion. In addition, dynamics of valves were calculated numerically using under-relaxed strong-coupling algorithm. Finally, the platelet activation results for BMV and MHV are compared with each other.

  6. Prostanoid production in the presence of platelet activation in hypoxic cocaine-treated rats.

    Science.gov (United States)

    Togna, G; Graziani, M; Sorrentino, C; Caprino, L

    1996-01-01

    To extend our previous in vitro data, we investigated the effects of cocaine on thromboxane A2 (TXA2) and prostacyclin (PGI2) production in vivo in the rat. To obtain the slight platelet activation that our in vitro experiments showed useful to highlight the effect of cocaine, we infused cocaine in rats in the presence of platelet-activating factors (circulation of blood through a perspex vascular device or by infusion of sodium arachidonate) and in various respiratory conditions. Experiments were conducted in rats breathing atmospheric air (normoxic conditions) and in rats breathing an oxygen-poor mixture (hypoxic conditions). In rats under hypoxic conditions cocaine invariably increased TXA2 plasma levels, whereas in normoxic conditions it increased TXA2 only in the presence of platelet-activating factors. Cocaine significantly increased PGI2 plasma levels in arachidonate-treated rats in hypoxic respiratory conditions; in normoxic conditions cocaine left PGI2 levels unchanged. These results support the hypothesis that in cocaine users who have concomitant pathological conditions able to activate platelets, such as atherosclerosis, coronary vasospasm or ischaemia, or both, cocaine may contribute to the onset of thrombotic phenomena by interfering with the prostaglandin system.

  7. Platelet activation and lipid peroxidation in patients with acute ischemic stroke

    NARCIS (Netherlands)

    F. van Kooten (Fop); G. Ciabattoni; C. Patrono; D.W.J. Dippel (Diederik); P.J. Koudstaal (Peter Jan)

    1997-01-01

    textabstractBACKGROUND AND PURPOSE: Both platelet activation and lipid peroxidation are potential sources of vasoactive eicosanoids that can be produced via the cyclooxygenase pathway, ie, thromboxane (TX) A2, or by free radical-catalyzed peroxidation of arachidonic acid, ie, isoprostanes. We invest

  8. Metabolic syndrome, platelet activation and the development of transient ischemic attack or thromboembolic stroke.

    Science.gov (United States)

    van Rooy, Mia-Jeanne; Pretorius, Etheresia

    2015-03-01

    Stroke is the second most common cause of mortality in the world today, where transient ischemic attack (TIA) is a period of focal ischemia, the symptoms of which resemble a thromboembolic stroke. Contrary to stroke, TIA symptoms typically last less than one hour and necrosis is absent. Stroke is often preceded by TIA, making it an important predictor of future ischemic events. The causal role of atherosclerosis in the development of TIA is well established, however, research indicates that the atherosclerotic process begins years earlier with the development of metabolic syndrome, which affects approximately 45% of the adult population worldwide. Metabolic syndrome is present if three or more of the following is present: increased waist circumference, increased triglycerides, decreased HDL, increased fasting glucose and hypertension. This syndrome causes systemic inflammation that activates the coagulation system and may cause the formation of pathological thrombi. The role of platelets in stroke has been studied and platelet activation pathways identified. ADP and thromboxane A(2) are the most common activators of platelets in normal physiology. Several pharmacological treatments have been employed to prevent the activation of platelets, the most common of which include aspirin and P2Y(12)-inhibitors. Although treatment is administered strokes and subsequent TIAs are very common in individuals that suffered an initial event. This indicates that research needs to be done in order to elucidate new therapeutic targets, but also to better treat ischemic events to not only decrease the amount of recurring events but also decrease stroke mortality worldwide.

  9. Cbl-b is a novel physiologic regulator of glycoprotein VI-dependent platelet activation.

    Science.gov (United States)

    Daniel, James L; Dangelmaier, Carol A; Mada, Sripal; Buitrago, Lorena; Jin, Jianguo; Langdon, Wallace Y; Tsygankov, Alexander Y; Kunapuli, Satya P; Sanjay, Archana

    2010-06-04

    Cbl-b, a member of the Cbl family of E3 ubiquitin ligases, plays an important role in the activation of lymphocytes. However, its function in platelets remains unknown. We show that Cbl-b is expressed in human platelets along with c-Cbl, but in contrast to c-Cbl, it is not tyrosine-phosphorylated upon glycoprotein VI (GPVI) stimulation. Cbl-b, unlike c-Cbl, is not required for Syk ubiquitylation downstream of GPVI activation. Phospholipase Cgamma2 (PLCgamma2) and Bruton's tyrosine kinase (BTK) are constituently associated with Cbl-b. Cbl-b-deficient (Cbl-b(-/-)) platelets display an inhibition in the concentration-response curve for GPVI-specific agonist-induced aggregation, secretion, and Ca(2+) mobilization. A parallel inhibition is found for activation of PLCgamma2 and BTK. However, Syk activation is not affected by the absence of Cbl-b, indicating that Cbl-b acts downstream of Syk but upstream of BTK and PLCgamma2. When Cbl-b(-/-) mice were tested in the ferric chloride thrombosis model, occlusion time was increased and clot stability was reduced compared with wild type controls. These data indicate that Cbl-b plays a positive modulatory role in GPVI-dependent platelet signaling, which translates to an important regulatory role in hemostasis and thrombosis in vivo.

  10. Elevation of Platelet and Monocyte Activity Markers of Atherosclerosis in Haemodialysis Patients Compared to Peritoneal Dialysis Patients

    Directory of Open Access Journals (Sweden)

    Ksenija Stach

    2017-01-01

    Full Text Available Purpose. The predominant cause of mortality in dialysis patients are cardiovascular events. Platelet and monocyte activity markers play an important role in cardiovascular mortality and were assessed and related to dialysis quality criteria in haemodialysis (HD and peritoneal dialysis (PD patients. Methods. For this prospective comparative study, HD patients (n=41 and PD patients (n=10 were included. In whole blood samples, surface expression of CD62P and CD40L on platelets, tissue factor binding on monocytes, and platelet-monocyte aggregates were measured by flow cytometry. Plasma levels of MCP-1, IL-6, TNFα, and soluble CD40L were analysed by enzyme-linked immunosorbent assay. Results. Haemodialysis patients showed a significantly higher CD62P expression on platelets (p=0.017, significantly higher amount of platelet-monocyte aggregates (p<0.0001, and significantly more tissue factor binding on monocytes (p<0.0001 compared to PD patients. In PD patients, a significant correlation between Kt/V and platelet CD40L expression (r=0.867; 0.001 and between Kt/V and platelet CD62P expression (r=0.686; p=0.028 was observed, while there was no significant correlation between Kt/V and tissue factor binding on monocytes and platelet-monocyte aggregates, respectively. Conclusion. Platelet and monocyte activity markers are higher in HD patients in comparison with those in PD patients, possibly suggesting a higher risk of cardiovascular morbidity and mortality.

  11. Elevation of Platelet and Monocyte Activity Markers of Atherosclerosis in Haemodialysis Patients Compared to Peritoneal Dialysis Patients.

    Science.gov (United States)

    Stach, Ksenija; Karb, Susanne; Akin, Ibrahim; Borggrefe, Martin; Krämer, Bernhard; Kälsch, Thorsten; Kälsch, Anna-Isabelle

    2017-01-01

    The predominant cause of mortality in dialysis patients are cardiovascular events. Platelet and monocyte activity markers play an important role in cardiovascular mortality and were assessed and related to dialysis quality criteria in haemodialysis (HD) and peritoneal dialysis (PD) patients. For this prospective comparative study, HD patients (n = 41) and PD patients (n = 10) were included. In whole blood samples, surface expression of CD62P and CD40L on platelets, tissue factor binding on monocytes, and platelet-monocyte aggregates were measured by flow cytometry. Plasma levels of MCP-1, IL-6, TNFα, and soluble CD40L were analysed by enzyme-linked immunosorbent assay. Haemodialysis patients showed a significantly higher CD62P expression on platelets (p = 0.017), significantly higher amount of platelet-monocyte aggregates (p < 0.0001), and significantly more tissue factor binding on monocytes (p < 0.0001) compared to PD patients. In PD patients, a significant correlation between Kt/V and platelet CD40L expression (r = 0.867; 0.001) and between Kt/V and platelet CD62P expression (r = 0.686; p = 0.028) was observed, while there was no significant correlation between Kt/V and tissue factor binding on monocytes and platelet-monocyte aggregates, respectively. Platelet and monocyte activity markers are higher in HD patients in comparison with those in PD patients, possibly suggesting a higher risk of cardiovascular morbidity and mortality.

  12. Antiplatelet activity of L-sulforaphane by regulation of platelet activation factors, glycoprotein IIb/IIIa and thromboxane A2.

    Science.gov (United States)

    Oh, Chung-Hun; Shin, Jang-In; Mo, Sang Joon; Yun, Sung-Jo; Kim, Sung-Hoon; Rhee, Yun-Hee

    2013-07-01

    L-sulforaphane was identified as an anticarcinogen that could produce quinine reductase and a phase II detoxification enzyme. In recent decades, multi-effects of L-sulforaphane may have been investigated, but, to the authors' knowledge, the antiplatelet activation of L-sulforaphane has not been studied yet.In this study, 2 μg/ml of collagen, 50 μg/ml of ADP and 5 μg/ml of thrombin were used for platelet aggregations with or without L-sulforaphane. L-sulforaphane inhibited the platelet aggregation dose-dependently. Among these platelet activators, collagen was most inhibited by L-sulforaphane, which markedly decreased collagen-induced glycoprotein IIb/IIIa activation and thromboxane A2 (TxA2) formation in vitro. L-sulforaphane also reduced the collagen and epinephrine-induced pulmonary embolism, but did not affect prothrombin time (PT) in vivo. This finding demonstrated that L-sulforaphane inhibited the platelet activation through an intrinsic pathway.L-sulforaphane had a beneficial effect on various pathophysiological pathways of the collagen-induced platelet aggregation and thrombus formation as a selective inhibition of cyclooxygenase and glycoprotein IIb/IIIa antagonist. Thus, we recommend L-sulforaphane as a potential antithrombotic drug.

  13. Thrombus imaging in a primate model with antibodies specific for an external membrane protein of activated platelets

    Energy Technology Data Exchange (ETDEWEB)

    Palabrica, T.M.; Furie, B.C.; Konstam, M.A.; Aronovitz, M.J.; Connolly, R.; Brockway, B.A.; Ramberg, K.L.; Furie, B.

    1989-02-01

    The activated platelet is a potential target for the localization of thrombi in vivo since, after stimulation and secretion of granule contents, activated platelets are concentrated at sites of blood clot formation. In this study, we used antibodies specific for a membrane protein of activated platelets to detect experimental thrombi in an animal model. PADGEM (platelet activation-dependent granule-external membrane protein), a platelet alpha-granule membrane protein, is translocated to the plasma membrane during platelet activation and granule secretion. Since PADGEM is internal in unstimulated platelets, polyclonal anti-PADGEM and monoclonal KC4 antibodies do not bind to circulating resting platelets but do interact with activated platelets. Dacron graft material incubated with radiolabeled KC4 or anti-PADGEM antibodies in the presence of thrombin-activated platelet-rich plasma bound most of the antibody. Imaging experiments with 123I-labeled anti-PADGEM in baboons with an external arterial-venous Dacron shunt revealed rapid uptake in the thrombus induced by the Dacron graft; control experiments with 123I-labeled nonimmune IgG exhibited minimal uptake. Deep venous thrombi, formed by using percutaneous balloon catheters to stop blood flow in the femoral vein of baboons, were visualized with 123I-labeled anti-PADGEM. Thrombi were discernible against blood pool background activity without subtraction techniques within 1 hr. No target enhancement was seen with 123I-labeled nonimmune IgG. 123I-labeled anti-PADGEM cleared the blood pool with an initial half-disappearance time of 6 min and did not interfere with hemostasis. These results indicate that radioimmunoscintigraphy with anti-PADGEM antibodies can visualize thrombi in baboon models and is a promising technique for clinical thrombus detection in humans.

  14. Changes in the level of cytosolic calcium, nitric oxide and nitric oxide synthase activity during platelet aggregation: an in vitro study in platelets from normal subjects and those with cirrhosis

    Indian Academy of Sciences (India)

    Sam Annie-JeyachristYn; Arumugam Geetha; Rajagopal Surendran

    2008-03-01

    Variceal bleeding due to abnormal platelet function is a well-known complication of cirrhosis. Nitric oxide-related stress has been implicated in the pathogenesis of liver cirrhosis. In the present investigation, we evaluated the level of platelet aggregation and concomitant changes in the level of platelet cytosolic calcium (Ca2+), nitric oxide (NO) and NO synthase (NOS) activity in liver cirrhosis. The aim of the present study was to investigate whether the production of NO by NOS and level of cytosolic Ca2+ influence the aggregation of platelets in patients with cirrhosis of the liver. Agonist-induced aggregation and the simultaneous changes in the level of cytosolic Ca2+, NO and NOS were monitored in platelets of patients with cirrhosis. Platelet aggregation was also measured in the presence of the eNOS inhibitor, diphenylene iodinium chloride (DIC). The level of agonist-induced platelet aggregation was significantly low in the platelets of patients with cirrhosis compared with that in platelets from normal subjects. During the course of platelet aggregation, concomitant elevation in the level of cytosolic Ca2+ was observed in normal samples, whereas the elevation was not significant in platelets of patients with cirrhosis. A parallel increase was observed in the levels of NO and NOS activity. In the presence of the eNOS inhibitor, platelet aggregation was enhanced and accompanied by an elevated calcium level. The inhibition of platelet aggregation in liver cirrhosis might be partly due to greater NO formation by eNOS. Defective Ca2+ release from the internal stores to the cytosol may account for inhibition of aggregation of platelets in cirrhosis. The NO-related defective aggregation of platelets in patients with cirrhosis found in our study is of clinical importance, and the underlying mechanism of such changes suggests a possible therapeutic strategy with cell-specific NO blockers.

  15. Supramolecular Chitosan Micro-Platelets Synergistically Enhance Anti-Candida albicans Activity of Amphotericin B Using an Immunocompetent Murine Model.

    Science.gov (United States)

    Grisin, Tiphany; Bories, Christian; Bombardi, Martina; Loiseau, Philippe M; Rouffiac, Valérie; Solgadi, Audrey; Mallet, Jean-Maurice; Ponchel, Gilles; Bouchemal, Kawthar

    2017-05-01

    The aim of this work is to design new chitosan conjugates able to self-organize in aqueous solution in the form of micrometer-size platelets. When mixed with amphotericin B deoxycholate (AmB-DOC), micro-platelets act as a drug booster allowing further improvement in AmB-DOC anti-Candida albicans activity. Micro-platelets were obtained by mixing oleoyl chitosan and α-cyclodextrin in water. The formulation is specifically-engineered for mucosal application by dispersing chitosan micro-platelets into thermosensitive pluronic(®) F127 20 wt% hydrogel. The formulation completely cured C. albicans vaginal infection in mice and had a superior activity in comparison with AmB-DOC without addition of chitosan micro-platelets. In vitro studies showed that the platelets significantly enhance AmB-DOC antifungal activity since the IC50 and the MIC90 decrease 4.5 and 4.8-times. Calculation of fractional inhibitory concentration index (FICI = 0.198) showed that chitosan micro-platelets act in a synergistic way with AmB-DOC against C. albicans. No synergy is found between spherical nanoparticles composed poly(isobutylcyanoacrylate)/chitosan and AmB-DOC. These results demonstrate for the first time the ability of flattened chitosan micro-platelets to have synergistic activity with AmB-DOC against C. albicans candidiasis and highlight the importance of rheological and mucoadhesive behaviors of hydrogels in the efficacy of the treatment.

  16. Early increase in DcR2 expression and late activation of caspases in the platelet storage lesion.

    Science.gov (United States)

    Plenchette, S; Moutet, M; Benguella, M; N'Gondara, J P; Guigner, F; Coffe, C; Corcos, L; Bettaieb, A; Solary, E

    2001-10-01

    Platelet transfusion is widely used to prevent bleeding in patients with severe thrombocytopenia. The maximal storage duration of platelet concentrates is usually 5 days, due to the platelet storage lesion that impairs their functions when stored for longer times. Some of the morphological and biochemical changes that characterize this storage lesion are reminiscent of cell death by apoptosis. The present study analyzed whether proteins involved in nucleated cell apoptosis could play a role in the platelet storage lesion. Storage of leukocyte-depleted platelets obtained by apheresis is associated with a late and limited activation of caspases, mainly caspase-3. This event correlates with an increased expression of the pro-apoptotic BH3-only protein Bim in the particulate fraction and a slight and late release of the pro-apoptotic mitochondrial protein Diablo/Smac in the cytosol. Platelets do not express the death receptors Fas, DR4 and DR5 on their plasma membrane, while the expression of the decoy receptor DcR2 increases progressively during platelet storage. Addition of low concentrations of the cryoprotector dimethylsulfoxide accelerates platelet caspase activation during storage, an effect that is partially prevented by the caspase inhibitor z-VAD-fmk. Altogether, DcR2 expression on the plasma membrane is an early event while caspase activation is a late event during platelet storage. These observations suggest that caspases are unlikely to account for the platelet storage lesion. As a consequence, addition of caspase inhibitors may not improve the quality of platelet concentrates stored in standard conditions.

  17. Release of transforming growth factor beta 1 and platelet derived growth factor type AB from canine platelet gels obtained by the tube method and activated with calcium salts

    OpenAIRE

    RF Silva; GC Santana; FOP Leme; JU Carmona; CMF Rezende

    2013-01-01

    The objectives of this study were: 1) to measure the concentrations of transforming growth factor beta 1 (TGF-β1) and platelet-derived growth factor type AB (PDGF-AB) in plasma and platelet gel (PG) activated with calcium salts (gluconate or chloride) in dogs, and 2) to determine correlations between cell results and growth factors (GF) concentrations. Blood samples were collected from fourteen Brazilian Fila dogs. EDTA was used to obtain whole blood and plasma while ACD-A solution was used t...

  18. Differences between mainstream and sidestream tobacco smoke extracts and nicotine in the activation and aggregation of platelets subjected to cardiovascular conditions in diabetes.

    Science.gov (United States)

    Yin, Wei; Rubenstein, David A

    2013-01-01

    Mainstream and sidestream tobacco smoke extracts have been shown to increase platelet activation directly. Furthermore, advanced glycation end products, which are present in the diabetic vasculature, have also been shown to enhance platelet activity. However, the combined effects of these two risk factors on platelet functions remain unclear. Platelets were exposed to tobacco extracts concurrently with advanced glycation end products. Timed samples were removed to assess the extent of platelet activity. The presence of smoke extracts enhanced platelet activity as compared to control conditions, this was especially prevalent for sidestream extracts. With the addition of irreversibly glycated albumin, there was an additive effect, further enhancing platelet responses. This was at least partially regulated by α-granule release and CD41 expression. The combination of cardiovascular risk factors can significantly enhance platelet activation and aggregation, and therefore it is possible to accelerate cardiovascular diseases through the interactions of multiple cardiovascular risk factors.

  19. Hydrogen peroxide stimulates the active transport of serotonin into human platelets

    Energy Technology Data Exchange (ETDEWEB)

    Bosin, T.R. (Indiana Univ., Bloomington (United States))

    1991-03-11

    The effect of hydrogen peroxide on the active transport of serotonin (5-HT) by human platelets was investigated. Platelets were exposed to either a single dose of H{sub 2}O{sub 2} or to H{sub 2}O{sub 2} generated by the glucose/glucose oxidase or xanthine/xanthine oxidase enzyme systems. H{sub 2}{sub 2} produced a rapid, dose-dependent and time-dependent increase in 5-HT transport which was maximal after a 2 min incubation and decreased with continued incubation. Catalase completely prevented H{sub 2}O{sub 2}-induced stimulation and fluoxetine totally blocked 5-HT uptake into stimulated platelets. The glucose/glucose oxidase and the xanthine/xanthine oxidase generating systems produced a similar response to that of H{sub 2}O{sub 2}. In the xanthine/xanthine oxidase system, superoxide dismutase failed to alter the stimulation, while catalase effectively prevented the response. The kinetics of 5-HT transport indicated that H{sub 2}O{sub 2} treatment did not alter the K{sub m} of 5-HT transport but significantly increased the maximal rate of 5-HT transport. These data demonstrated that exposure of human platelets to H{sub 2}O{sub 2} resulted in a stimulation of the active transport of 5-HT and suggested that H{sub 2}O{sub 2} may function to regulate this process.

  20. Detection of active left ventricular thrombosis during acute myocardial infarction using indium-111 platelet scintigraphy

    Energy Technology Data Exchange (ETDEWEB)

    Ezekowitz, M.D.; Kellerman, D.J.; Smith, E.O.; Streitz, T.M.

    1984-07-01

    Platelet scintigraphy with radioactive indium-111 may be used both to identify and to reflect the activity of thrombin in vivo in man. Forty-one patients with acute myocardial infarction were studied for active left ventricular thrombosis by platelet scintigraphy and followed until in-hospital death, discharge, or same-admission cardiac surgery for evidence of systemic embolization. Group 1 (n . 29) had transmural myocardial infarctions, of which 21 were anterior and eight were inferior. Group 2 (n . 12) had subendocardial myocardial infarctions. Those with subendocardial and transmural inferior myocardial infarctions had neither left ventricular thrombosis nor emboli. Ten (48 percent) of 21 with anterior transmural myocardial infarctions had left ventricular thrombosis by platelet scintigraphy. Three with and one without such thrombosis by scintigraphy had acute neurologic episodes. In the group with anterior myocardial infarctions, seven of ten patients with and four of 11 without left ventricular thrombosis received heparin subcutaneously. We conclude that platelet scintigraphy may be used to monitor antiplatelet and anticoagulant therapy in patients with anterior transmural myocardial infarctions who are at risk for left ventricular thrombosis and systemic embolization.

  1. Ingestion of onion soup high in quercetin inhibits platelet aggregation and essential components of the collagen-stimulated platelet activation pathway in man: a pilot study

    NARCIS (Netherlands)

    Hubbard, G.; Wolffram, S.; Vos, de C.H.; Bovy, A.G.; Gibbins, J.; Lovegrove, J.

    2006-01-01

    Epidemiological data suggest that those who consume a diet rich in quercetin-containing foods may have a reduced risk of CVD. Furthermore, in vitro and ex vivo studies have observed the inhibition of collagen-induced platelet activation by quercetin. The aim of the present study was to investigate t

  2. Technetium 99m-labeled annexin v scintigraphy of platelet activation in vegetations of experimental endocarditis

    Energy Technology Data Exchange (ETDEWEB)

    Rouzet, F.; Sarda-Mantel, L.; Le Guludec, D. [Nucl Med Serv, Grp Hosp Bichat Claude Bernard, AP-HP, Paris (France); Rouzet, F.; Sarda-Mantel, L.; LeGuludec, D. [Univ Denis Diderot Paris 7, UMR S773, Paris (France); Rouzet, F.; Sarda-Mantel, L.; Le Guludec, D. [INSERM, U773, Paris (France); Hernandez, M.D.; Louedec, L.; Michel, J.B. [Univ Paris 07, CHU Xavier Bichat, INSERM, U698, Paris (France); Hervatin, F. [CEA, DSV, DRM, SHFJ, Orsay (France); Lefort, A.; Fantin, B. [Univ Denis Diderot Paris 7, EA 3964, Paris (France); Duval, X. [Univ Denis Diderot Paris 7, INSERM, CIC 007, Paris (France); Duval, X. [Univ Denis Diderot Paris 7, AP-HP, Grp Hosp Bichat Claude Bernard, Ctr Invest Clin, Paris (France); Hernandez, M.D. [Univ Guadalajara, DeptPathol, Guadalajara 44430, Jalisco (Mexico)

    2008-07-01

    Background: The pathophysiology of infective endocarditis involves a pathogen/host tissue interaction, leading to formation of infected thrombotic vegetations. Annexin V is a ligand of phosphatidyl-serines exposed by activated platelets and apoptotic cells. Because vegetations are platelet-fibrin clots in which platelet pro-aggregant activity is enhanced by bacterial colonization, we investigated the ability of annexin V labeled with technetium {sup 99m}Tc ({sup 99m}Tc-ANX) to provide functional imaging of these vegetations in experimental models of infective endocarditis. This ability was assessed in rabbits and rats because of the different interest of these 2 species in preclinical analysis. Methods and Results: Non-bacterial thrombotic endocarditis was induced with the use of a catheter left indwelling through the aortic or tricuspid valve, and animals were injected with either a bacterial inoculum or saline. Scintigraphic investigations were performed 5 days later and showed a higher {sup 99m}Tc-ANX uptake by vegetations in infected versus non-infected animals (ratio,1.3 for in vivo acquisitions and 2 for autoradiography; P {<=} 0.0001 for all), whereas no significant uptake was present in controls. Right-sided endocarditis was associated with pulmonary uptake foci corresponding to emboli. Histological analysis of vegetations showed a specific uptake of {sup 99m}Tc-ANX at the interface between circulating blood and vegetation. In parallel, underlying myocardial tissue showed myocyte apoptosis and mucoid degeneration, without extracellular matrix degradation at this stage. Conclusions: {sup 99m}Tc-ANX is suitable for functional imaging of platelet-fibrin vegetations in endocarditis, as well as embolic events. {sup 99m}Tc-ANX uptake reflects mainly platelet activation in the luminal layer of vegetations. This uptake is enhanced by bacterial colonization. (authors)

  3. Critical temperature ranges of hypothermia-induced platelet activation: possible implications for cooling patients in cardiac surgery.

    Science.gov (United States)

    Straub, Andreas; Breuer, Melanie; Wendel, Hans P; Peter, Karlheinz; Dietz, Klaus; Ziemer, Gerhard

    2007-04-01

    Cooling of the patient is routinely applied in cardiac surgery to protect organs against ischemia. Hypothermia induces activation of platelets, but the effects of temperatures such as used during cardiac surgery are not well described. To investigate this in an in-vitro study heparinized whole blood was incubated at different temperatures (37 degrees C, 34.5 degrees C, 32 degrees C, 29.5 degrees C, 27 degrees C, 24.5 degrees C, 22 degrees C, 19.5 degrees C and 17 degrees C). The effect of these temperatures on aggregation, P-selectin expression, GP IIb/IIIa activation and platelet microparticle (PMP) formation of unstimulated and ADP-stimulated platelets of 36 subjects was evaluated in flow cytometry. A four-parametric logistic model was fitted to depict the temperature effect on platelet parameters. Lower temperatures increased aggregates, P-selectin expression, and GP IIb/IIIa activation. The number of PMPs decreases with hypothermia. Additional experiments revealed a slight influence of heparin on platelet P-selectin expression but excluded an effect of this anticoagulant on the other evaluated parameters. Threshold temperatures, which mark 5% changes of platelet parameters compared to values at 37 degrees C, were calculated. On ADP-stimulated platelets the thresholds for P-selectin expression and GP IIb/IIa activation are 34.0 degrees C and 36.4 degrees C, respectively, and lie in the temperature range routinely applied in cardiac surgery. Hypothermia-induced platelet activation may develop in most patients undergoing cardiac surgery, possibly resulting in thromboembolic events, coagulation defects, and proinflammatory leukocyte bridging by P-selectin bearing platelets and PMPs. These findings suggest that pharmacological protection of platelets against hypothermia-induced damage may be beneficial during cardiac surgery.

  4. Calidad del plasma rico en plaquetas: estudio de la activación plaquetaria Platelet-rich plasma quality: a study on platelet activation

    Directory of Open Access Journals (Sweden)

    C. Sáez-Torres Barroso

    2007-08-01

    Full Text Available Objetivo. El plasma rico en plaquetas (PRP es utilizado de forma cada vez más frecuente en técnicas quirúrgicas de regeneración tisular. No obstante, el procesamiento de la sangre hasta obtener PRP puede desencadenar la activación prematura de las plaquetas y la pérdida de los factores bioactivos. En este trabajo estudiamos la calidad de los concentrados de plaquetas obtenidos siguiendo la técnica de doble centrifugación en tubo. Método. Se someten 50 ml de sangre a una primera centrifugación a 200g 10 minutos, se recoge el sobrenadante y se centrifuga a 700g 15 minutos. Posteriormente, tras eliminar las 2/3 partes del plasma, se resuspenden las plaquetas y se analiza el grado de enriquecimiento, el estado de activación y la reserva funcional de las plaquetas. Resultados. El enriquecimiento en plaquetas del PRP fue de 364±177% (n=45 respecto de los niveles presentes en sangre total. Mediante el estudio de la expresión de CD62 por citometría de flujo se determinó el porcentaje de plaquetas activadas en las muestras de 8 donantes. Mientras que en la sangre no procesada se detectó un 2,7% de plaquetas activadas, tras la preparación del PRP éste era sólo de 3,6%, aumentando hasta el 16% en el concentrado almacenado toda la noche a 22º C. Tras la estimulación con trombina el porcentaje de plaquetas activadas fue de 96,2%. Conclusión. Este protocolo de preparación de PRP no produce una activación significativa de las plaquetas. La respuesta a la estimulación con trombina de los concentrados indica un buen estado de reserva plaquetaria.Objective. Platelet Rich Plasma (PRP is an autologous preparation currently used in oral and maxillofacial reconstructive surgery. Blood collection and preparation of platelet concentrates may lead to platelet activation and the premature loss of their granular load. In this study, we have analyzed the quality of the PRP obtained from a small volume of whole blood through a double centrifugation

  5. Interactive protein network of FXIII-A1 in lipid rafts of activated and non-activated platelets.

    Science.gov (United States)

    Rabani, Vahideh; Montange, Damien; Davani, Siamak

    2016-09-01

    Lipid-rafts are defined as membrane microdomains enriched in cholesterol and glycosphingolipids within platelet plasma membrane. Lipid raft-mediated clot retraction requires factor XIII and other interacting proteins. The aim of this study was to investigate the proteins that interact with factor XIII in raft and non-raft domains of activated and non-activated platelet plasma membrane. By lipidomics analysis, we identified cholesterol- and sphingomyelin-enriched areas as lipid rafts. Platelets were activated by thrombin. Proteomics analysis provided an overview of the pathways in which proteins of rafts and non-rafts participated in the interaction network of FXIII-A1, a catalytic subunit of FXIII. "Platelet activation" was the principal pathway among KEGG pathways for proteins of rafts, both before and after activation. Network analysis showed four types of interactions (activation, binding, reaction, and catalysis) in raft and non-raft domains in interactive network of FXIII-A1. FXIII-A1 interactions with other proteins in raft domains and their role in homeostasis highlight the specialization of the raft domain in clot retraction via the Factor XIII protein network.

  6. Stimulation of Leishmania tropica protein kinase CK2 activities by platelet-activating factor (PAF).

    Science.gov (United States)

    Dutra, Patricia M L; Vieira, Danielle P; Meyer-Fernandes, Jose R; Silva-Neto, Mario A C; Lopes, Angela H

    2009-09-01

    Leishmania tropica is one of the causative agents of cutaneous leishmaniasis. Platelet-activating factor (PAF) is a phospholipid mediator in diverse biological and pathophysiological processes. Here we show that PAF promoted a three-fold increase on ecto-protein kinase and a three-fold increase on the secreted kinase activity of L. tropica live promastigotes. When casein was added to the reaction medium, along with PAF, there was a four-fold increase on the ecto-kinase activity. When live L. tropica promastigotes were pre-incubated for 30 min in the presence of PAF-plus casein, a six-fold increase on the secreted kinase activity was observed. Also, a protein released from L. tropica promastigotes reacted with polyclonal antibodies for the mammalian CK2 alpha catalytic subunit. Furthermore, in vitro mouse macrophage infection by L. tropica was doubled when promastigotes were pre-treated for 2 h with PAF. Similar results were obtained when the interaction was performed in the presence of purified CK2 or casein. TBB and DRB, CK2 inhibitors, reversed PAF enhancement of macrophage infection by L. tropica. WEB 2086, a competitive PAF antagonist, reversed all PAF effects here described. This study shows for the first time that PAF promotes the activation of two isoforms of CK2, secreted and membrane-bound, correlating these activities to infection of mouse macrophages.

  7. Shape changes induced by biologically active peptides and nerve growth factor in blood platelets of rabbits.

    Science.gov (United States)

    Gudat, F; Laubscher, A; Otten, U; Pletscher, A

    1981-11-01

    1 Nerve growth factor (NGF), substance P (SP) and thymopoietin all caused shape change reactions of rapid onset in rabbit platelets. NGF had the highest maximal effect, and SP the lowest EC50 (concentration causing half maximal shape change). The action of SP was reversible within 5 min, whereas that of NGF lasted for at least 1 h. A series of other peptides were inactive. 2 After preincubation of platelets with SP, a second application of SP no longer caused a shape change reaction, whereas the effect of NGF was not influenced. 3 An oxidized NGF-derivative without biological activity did not cause a shape change reaction, neither did epidermal growth factor. 4 Prostaglandin E1 (PGE1) and pretreatment of the platelets with 3% butanol, which counteract the shape changes caused by 5-hydroxytryptamine (5-HT) and adenosine 3',5'-diphosphate, also antagonized those induced by NGF and SP. Neither heparin nor methysergide, an antagonist of 5-HT-receptors, influenced the shape change induced by NGF or SP. The action of NGF was also antagonized by a specific antibody to NGF. 5 Thymopoietin, like the basic polypeptide polyornithine (mol. wt. 40,000) was not antagonized by PGE1 and butanol. Heparin, which counteracted the effect of polyornithine, did not influence that of thymopoietin. 6 In conclusion, different modes of action are involved in the shape change of blood platelets induced by polypeptides and proteins. SP and NGF may act by stimulating specific membrane receptors.

  8. Pneumatic tube system transport does not alter platelet function in optical and whole blood aggregometry, prothrombin time, activated partial thromboplastin time, platelet count and fibrinogen in patients on anti-platelet drug therapy

    Science.gov (United States)

    Enko, Dietmar; Mangge, Harald; Münch, Andreas; Niedrist, Tobias; Mahla, Elisabeth; Metzler, Helfried; Prüller, Florian

    2017-01-01

    Introduction The aim of this study was to assess pneumatic tube system (PTS) alteration on platelet function by the light transmission aggregometry (LTA) and whole blood aggregometry (WBA) method, and on the results of platelet count, prothrombin time (PT), activated partial thromboplastin time (APTT), and fibrinogen. Materials and methods Venous blood was collected into six 4.5 mL VACUETTE® 9NC coagulation sodium citrate 3.8% tubes (Greiner Bio-One International GmbH, Kremsmünster, Austria) from 49 intensive care unit (ICU) patients on dual anti-platelet therapy and immediately hand carried to the central laboratory. Blood samples were divided into 2 Groups: Group 1 samples (N = 49) underwent PTS (4 m/s) transport from the central laboratory to the distant laboratory and back to the central laboratory, whereas Group 2 samples (N = 49) were excluded from PTS forces. In both groups, LTA and WBA stimulated with collagen, adenosine-5’-diphosphate (ADP), arachidonic acid (AA) and thrombin-receptor-activated-peptide 6 (TRAP-6) as well as platelet count, PT, APTT, and fibrinogen were performed. Results No statistically significant differences were observed between blood samples with (Group 1) and without (Group 2) PTS transport (P values from 0.064 – 0.968). The AA-induced LTA (bias: 68.57%) exceeded the bias acceptance limit of ≤ 25%. Conclusions Blood sample transportation with computer controlled PTS in our hospital had no statistically significant effects on platelet aggregation determined in patients with anti-platelet therapy. Although AA induced LTA showed a significant bias, the diagnostic accuracy was not influenced. PMID:28392742

  9. Research Influence Biological Active Agents in the Course of Regulation of Functional Activity of Platelets and System of a Haemostasis

    Directory of Open Access Journals (Sweden)

    Nozim N. Khoshimov

    2015-06-01

    Full Text Available It is shown that the flavonoid pulikarin suppresses activity of an adenylate cyclase and reduces level intracellular [Ca2+], perhaps its effect is connected with inhibition of a gain of cytoplasmatic Ca2+ as at the expense of its entrance outside, and release from intracellular storages. Perhaps, oppression of fluorescence of membrane-bound Ca2+ is connected with inhibition of a pulikarin of release of calcium from intracellular depots. The inhibiting effect of a pulikarin on ADP-induced aggregation of platelets is connected with oppression of a gain of cytoplasmatic concentration of Ca2+ from depot of platelets.

  10. Suppressive effect of CORM-2 on LPS-induced platelet activation by glycoprotein mediated HS1 phosphorylation interference.

    Directory of Open Access Journals (Sweden)

    Dadong Liu

    Full Text Available In recent years, it has been discovered that septic patients display coagulation abnormalities. Platelets play a major role in the coagulation system. Studies have confirmed that carbon monoxide (CO has important cytoprotective and anti-inflammatory function. However, whether CO could alter abnormal activation of platelets and coagulation and thereby reduce the incidence of mortality during sepsis has not been defined. In this report, we have used CO-releasing molecules (CORM-2 to determine whether CO inhibits LPS-induced abnormal activation of platelets and have explored the potential mechanisms. LPS was used to induce activation of platelets in vitro, which were purified from the peripheral venous blood of healthy adult donors. CORM-2 was applied as a potential therapeutic agent. CORM-2 preconditioning and delayed treatment were also studied. We found that in the LPS groups, the function of platelets such as spreading, aggregation, and release were enhanced abnormally. By contrast, the platelets in the CORM-2 group were gently activated. Further studies showed that the expression of platelet membrane glycoproteins increased in the LPS group. Coincidently, both hematopoietic lineage cell-specific protein 1 and its phosphorylated form also increased dramatically. These phenomena were less dramatically seen in the CORM-2 groups. Taken together, we conclude that during LPS stimulation, platelets were abnormally activated, and this functional state may be associated with the signal that is transmitted between membrane glycoproteins and HS1. CORM-released CO suppresses the abnormal activation of platelets by interfering with glycoprotein-mediated HS1 phosphorylation.

  11. Mechanism study of endothelial protection and inhibits platelet activation of low molecular weight fucoidan from Laminaria japonica

    Science.gov (United States)

    Chen, Anjin; Zhang, Fang; Shi, Jie; Zhao, Xue; Yan, Meixing

    2016-10-01

    Several studies have indicated that fucoidan fractions with low molecular weight and different sulfate content from Laminaria japonica could inhibit the activation of platelets directly by reducing the platelet aggregation. To explore the direct effect of LMW fucoidan on the platelet system furthermore and examine the possible mechanism, the endothelial protection and inhibits platelet activation effects of two LMW fucoidan were investigated. In the present study, Endothelial injury model of rats was made by injection of adrenaline (0.4 mg kg-1) and human umbilical vein endothelial cells were cultured. vWF level was be investigated in vivo and in vitro as an important index of endothelial injury. LMW fucoidan could significantly reduce vWF level in vascular endothelial injury rats and also significantly reduce vWF level in vitro. The number of EMPs was be detected as another important index of endothelial injury. The results showed that LMW fucoidan reduced EMPs stimulated by tumor necrosis factor. In this study, it was found that by inhibiting platelet adhesion, LMW fucoidan played a role in anti-thrombosis and the specific mechanism of action is to inhibit the flow of extracellular Ca2+. All in a word, LMW fucoidan could inhibit the activation of platelets indirectly by reducing the concentration of EMPs and vWF, at the same time; LMW fucoidan inhibited the activation of platelets directly by inhibiting the flow of extracellular Ca2+.

  12. The relationship between the level of activation markers of platelets in peripheral blood around operation and lung cancer%肺癌患者外周血血小板活化标志物水平及其临床意义

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Objective: To investigate the relationship between the activation markers of platelets and the lung cancer.Methods: Based on international stages of lung cancer in 1997, lung cancer patients of 120 cases diagnosed by pathology as well as with operation indication were selected as the experimental group.During the process of experiment, 60 cases concluded as healthy in the physical examination were chosen as control group.The activation markers of platelets were detected by FCM method.The experimental result would be processed by SPSS 11.5.Results: The level of activation markers of platelets in peripheral blood of lung cancer patients was significantly higher than those healthy people(P<0.01).The level of activation markers of platelets in peripheral blood of lung cancer patients on the seventh postoperative day was significantly lower than that before operation and on the first postoperative day(P<0.01).The level of activation markers of platelets in peripheral blood of lung cancer patients was closely related to the size of the primary tumor, lymph node status and stages, but not to the grade of cell differentiation, type of tumor, age, sex of the patients(P>0.05).Conclusion: Elevation of the level of activation markers of platelets in peripheral blood exists in lung cancer patients and the levels of activation marker of platelets plays an important role in tumor growth and lymphatic metastasis.The levels of activation markers of platelets maybe a predictor for prognosis.

  13. Oxidative damage and platelet activation as new predictors of mobility disability and mortality in elders.

    Science.gov (United States)

    Cesari, Matteo; Kritchevsky, Stephen B; Leeuwenburgh, Christiaan; Pahor, Marco

    2006-01-01

    Mobility disability is an early phase of the disablement process in older adults, and represents a major risk factor for physical disability and mortality. Pathophysiological mechanisms responsible for the onset of mobility limitation are still largely unknown. Oxidative damage, responsible for the disruption of the equilibrium of biological systems by damaging major constituent molecules, might play an important role in the pathway leading to major health-related events. It has been suggested the existence of a vicious cycle involving oxidative damage, platelet activation, and inflammation as promoter of pathophysiological changes occurring with aging. This hypothesis is based on the following observations: (a) oxidative damage is associated with diseases and clinical conditions potentially leading to disability and mortality; (b) oxidative damage is associated with platelet activation, and a vicious cycle involving oxidative damage, platelet activation, and inflammation has been demonstrated in several metabolic disorders potentially leading to mobility disability; (c) the age-related physical decline may be associated to the oxidative damage due to the excess of free radicals; (d) antioxidant defense and behavioral factors (e.g., physical activity, dietary restriction, smoking cessation) play an important role in the reduction of oxidative damage levels and are associated with improved physical performance and muscle strength.

  14. Oxidatively fragmented phosphatidylcholines activate human neutrophils through the receptor for platelet-activating factor.

    Science.gov (United States)

    Smiley, P L; Stremler, K E; Prescott, S M; Zimmerman, G A; McIntyre, T M

    1991-06-15

    Platelet-activating factor (PAF, 1-O-alkyl-2-acetyl-sn-glycero-3-phosphocholine) activates neutrophils (polymorphonuclear leukocytes, PMN) through a receptor that specifically recognizes short sn-2 residues. We oxidized synthetic [2-arachidonoyl]phosphatidylcholine to fragment and shorten the sn-2 residue, and then examined the phospholipid products for the ability to stimulate PMN. 1-Palmitoyl-2-arachidonoyl-sn-glycero-3-phosphocholine was fragmented by ozonolysis to 1-palmitoyl-2-(5-oxovaleroyl)-sn-glycero-3-phosphocholine. This phospholipid activated human neutrophils at submicromolar concentrations, and is effects were inhibited by specific PAF receptor antagonists WEB2086, L659,989, and CV3988. 1-Palmitoyl-2-arachidonoyl-sn-glycero-3-phosphocholine next was fragmented by an uncontrolled free radical-catalyzed reaction: it was treated with soybean lipoxygenase to form its sn-2 15-hydroperoxy derivative (which did not activate neutrophils) and then allowed to oxidize under air. The secondary oxidation resulted in the formation of numerous fragmented phospholipids (Stremler, K. E., Stafforini, D. M., Prescott, S. M., and McIntyre, T. M. (1991) J. Biol. Chem. 266, 11095-11103), some of which activated PMN. Hydrolysis of sn-2 residues with phospholipase A2 destroyed biologic activity, as did hydrolysis with PAF acetylhydrolase. PAF acetylhydrolase is specific for short or intermediate length sn-2 residues and does not hydrolyze the starting material (Stremler, K. E., Stafforini, D. M., Prescott, S. M., and McIntyre, T. M. (1991) J. Biol. Chem. 266, 11095-11103). Neutrophil activation was completely blocked by L659,989, a specific PAF receptor antagonist. We conclude that diacylphosphatidylcholines containing an sn-2 polyunsaturated fatty acyl residue can be oxidatively fragmented to species with sn-2 residues short enough to activate the PAF receptor of neutrophils. This suggests a new mechanism for the appearance of biologically active phospholipids, and shows

  15. Dragon's Blood extract has antithrombotic properties, affecting platelet aggregation functions and anticoagulation activities.

    Science.gov (United States)

    Xin, Nian; Li, Yu-Juan; Li, Yan; Dai, Rong-Ji; Meng, Wei-Wei; Chen, Yan; Schlappi, Michael; Deng, Yu-Lin

    2011-05-17

    Dragon's Blood from Dracaena cochinchinensis (Lour.) S.C. Chen (Yunnan, China), as a traditional Chinese medicinal herb, was shown to have certain antithrombotic effects. A new preparation process was used to extract effective components from Dragon's Blood. A 95% ethanol extract A (EA) and a precipitate B (PB) fraction were obtained and compared. Reliability of the preparation process was validated by pharmacodynamic experiments. A rat/mouse thrombosis and blood stasis model was developed for this study, and EA and PB effects on thrombosis, platelet functions and blood coagulation activities were analyzed. It was observed that the EA fraction had significantly better inhibitory effects than the PB fraction on thrombosis (pDragon's Blood contained pharmacologically effective compounds with antithrombotic effects, partially improving platelet function and anticoagulation activity. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

  16. PLATELET ACTIVATION AND ENDOTHELIAL CELL IMPAIRMENT ON ADRENOGLUCOCORTISONE-INDUCED OSTEONECROSIS

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Objective To investigate the effects of the platelet activation and the endothelial cell impairment on the osteonecrosis. Methods The contents of TXB2,6-keto-PGF1a, GMP-140 and TM in different periods of animal models of adrenoglucocortisone-induced osteonerosis were measured by the radio-immunity method. Results The contents in group B increased dramatically from 24h after the injection of adrenoglucocortisone, and the contents of GMP-140 and TM from 3d after injection increased with significant difference from group A. Conclusion The results suggest that the early emergence of the platelet activation and endothelial cell impairment models induced by horse serum and adrenoglucocortisone plays a role in the formation of the osteonecrosis.

  17. Activation-dependent surface expression of gC1qR/p33 on human blood platelets.

    Science.gov (United States)

    Peerschke, Ellinor I B; Murphy, Tara K; Ghebrehiwet, Berhane

    2003-02-01

    GC1qR/p33 (gC1qR) is expressed by a variety of somatic and cultured cells, including blood platelets. It interacts with several cellular, viral, bacterial, and plasma proteins, suggesting a potential role in thrombosis, inflammation, and infection. Considerable controversy has surrounded the surface membrane localization of gC1qR, however, since its cDNA sequence does not predict a traditional membrane-anchoring domain, and bears a typical mitochondrial targeting sequence. The present study examined gC1qR expression on resting and activated human blood platelets using flow cytometry and confocal microscopy with two monoclonal antibodies, 74.5.2 and 60.11, directed against gC1qR C-terminal amino acids 204-218, and N-terminal amino acids 76-93, respectively. Unstimulated platelets reacted minimally with either antibody. In contrast, platelet activation with TRAP, epinephrine, or ADP produced markedly increased gC1qR expression as reflected by 74.5.2 binding but not 60.11 binding. Platelet activation was verified using PAC-1 and anti CD 62 antibodies. Whereas PAC-1 binding to activated platelets could be reversed following platelet incubation with PGE1, 74.5.2 binding remained unchanged, suggesting the sustained expression of gC1qR following platelet stimulation. The data further demonstrate that detection of cell surface gC1qR may be dependent on antibody specificity. The ability of gC1qR to bind proteins involved in complement, coagulation, and kinin systems, as well as viral and bacterial pathogens including S. aureus protein A, supports the hypothesis that gC1qR expressed on activated platelets may contribute directly to thrombosis, inflammation, and endovascular infections.

  18. Human platelets utilize cycloxygenase-1 to generate dioxolane A3, a neutrophil activating eicosanoid

    OpenAIRE

    Hinz, Christine; Aldrovandi, MacEler; Alam, Saydul; Slatter, David; Lauder, Sarah Nicol; Allen-Redpath, Keith; Collins, Peter William; Thomas, Christopher P.; O'Donnell, Valerie Bridget

    2016-01-01

    Eicosanoids are important mediators of fever, pain, and inflammation that modulate cell signaling during acute and chronic disease. We show by using lipidomics that thrombin-activated human platelets generate a new type of eicosanoid that both stimulates and primes human neutrophil integrin (Mac-1) expression, in response to formylmethionylleucylphenylalanine. Detailed characterization proposes a dioxolane structure, 8-hydroxy-9,11-dioxolane eicosatetraenoic acid (dioxolane A3, DXA3). The lip...

  19. Cognitive Stimulation Modulates Platelet Total Phospholipases A2 Activity in Subjects with Mild Cognitive Impairment.

    Science.gov (United States)

    Balietti, Marta; Giuli, Cinzia; Fattoretti, Patrizia; Fabbietti, Paolo; Postacchini, Demetrio; Conti, Fiorenzo

    2016-01-01

    We evaluated the effect of cognitive stimulation (CS) on platelet total phospholipases A2 activity (tPLA2A) in patients with mild cognitive impairment (MCI_P). At baseline, tPLA2A negatively correlated with Mini-Mental State Examination score (MMSE_s): patients with MMSE_s cognitive conditions of MCI_P, and that CS acts selectively on subjects with a dysregulated tPLA2A.

  20. Platelets augment respiratory burst in neutrophils activated by selected species of gram-positive or gram-negative bacteria.

    Directory of Open Access Journals (Sweden)

    Kamila Pytel

    2008-12-01

    Full Text Available Neutrophils and platelets circulate in blood system and play important physiological roles as part of immunological system. Neutrophils are the first line of host defense against various intruders, and platelets are satellite cells cooperating with other components of defense system. Recent studies report about the cooperation among these types of cells. We analyzed the effect of platelets on oxygen burst in neutrophils triggered by Staphylococcus aureus and Escherichia coli bacteria in vitro. The effect of platelets on oxygen burst in neutrophils was measured by luminol enhanced chemiluminescence. Opsonized and non-opsonized bacteria were used as activators. Activation of neutrophils with live non-opsonized and opsonized bacteria in the presence of platelets increased the oxygen burst as compared to the same system without platelets. The gram-positive bacteria (Staphylococcus aureus were causing higher activation than gram-negative bacteria (Escherichia coli. This work demonstrate that platelets potentate the response of neutrophils augmenting their respiratory burst in vitro when triggered by bacteria.

  1. Dialyzer membranes: effect of surface area and chemical modification of cellulose on complement and platelet activation.

    Science.gov (United States)

    Mahiout, A; Meinhold, H; Kessel, M; Schulze, H; Baurmeister, U

    1987-04-01

    Using an ex vivo model, the effects of membrane composition and surface area on both the complement system (as reflected by plasma C3a levels) and platelets [as indicated by plasma concentrations of thromboxane B2 (TXB2) and platelet factor 4 (PF4)] were studied. In this model, polyacrylonitrile (PAN) was associated with less complement activation than cuprammonium cellulose (CC). A new "modified cellulose" (MC) membrane, in which a small number of the free hydroxyl groups on cellulose are substituted with a tertiary amino compound, was also associated with a low degree of complement activation, similar to that with PAN. However, the extent of hydroxyl group substitution in four MC membrane subtypes did not correlate with the reduction in complement activation. In studies using CC, the amount of generated C3a correlated with the membrane surface area, although the relationship was curvilinear. Plasma concentrations at the "dialyzer" outlet of TXB2 and PF4 were similar with CC, PAN, and MC. In studies with the MC subtypes, increasing the extent of hydroxyl group substitution paradoxically increased, albeit slightly, the amount of TXB2 generation. In studies with CC, a linear relationship between membrane surface area and TXB2 generation was found. The results suggest a dissociation between platelet and complement effects among different dialyzer membranes, and underline the importance of membrane surface area.

  2. Effects of hormone replacement therapy on platelet activation in postmenopausal women

    Institute of Scientific and Technical Information of China (English)

    古健; 杨冬梓; 王良岸; 尹松梅; 邝健全

    2003-01-01

    Objective To assess the effects of hormone replacement therapy (HRT) on platelet activation in postmenopausal women compared with premenopausal women. Methods The expressions of CD41 and CD62P in fifteen postmenopausal women before and after HRT were detected using flow cytometry (FCM), with fifteen premenopausal women with a mean age of 47 years as controls.Results The expressions of CD41 and CD62P in postmenopausal women were higher than those in the control group. CD62P(%), CD62P(I) and CD41 were reduced from 36.40±5.9, 37.75±5.8, and 470.11±74.0 to 27.97±5.6, 26.64±4.9, and 303.23±72.8 after six months of HRT (P<0.05). Conclusions Platelet activation in postmenopausal women was higher than in premenopausal women and was reduced significantly after six months of HRT. HRT may have a favorable effect on reduction of platelet activity.

  3. Protective Mechanisms of Guanosine from Solanum lycopersicum on Agonist-Induced Platelet Activation: Role of sCD40L

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    Iván Palomo

    2013-07-01

    Full Text Available In the past 30 years, only three natural products have been sources of new drugs with antiplatelet activity. In this study, we have demonstrated for the first time that guanosine from Solanum lycopersicum possesses antiplatelet (secretion, spreading, adhesion and aggregation activity in vitro and inhibition of platelet inflammatory mediator of atherosclerosis (sCD40L. According to ADP-induced platelet aggregation inhibiting, the total extract residue was fractionated by liquid chromatography/phase separation, affording an aqueous fraction. This fraction was subjected to repeated permeation over Sephadex LH-20 and semi-preparative TLC. The isolated compound finally obtained was identified as guanosine on the basis of its UV-spectra, HPLC and 1H-NMR data. Guanosine concentration dose-dependently (1 to 4 mmol/L inhibited platelet secretion and aggregation induced by ADP and collagen. Spread of human platelets on collagen in the presence of guanosine was fully inhibited. After incubation of whole blood with guanosine, the platelet adhesion and aggregation under flow conditions was inhibited concentration dependently (0.2 to 2 mmol/L. At the same concentrations that guanosine inhibits platelet aggregation, levels of sCD40L were significantly decreased. Guanosine is thus likely to exert significant protective effects in thromboembolic-related disorders by inhibiting platelet aggregation.

  4. Psychobiology of borderline personality traits related to subtypes of eating disorders: a study of platelet MAO activity.

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    Díaz-Marsá, Marina; Carrasco, Jose L; de Anta, Laura; Molina, Rosa; Sáiz, Jerónimo; Cesar, Jesus; López-Ibor, Juan J

    2011-12-30

    Increased and decreased levers of platelet monoamine oxidase (MAO) activity have been reported in patients with eating disorders, indicating abnormalities of the serotonin turnover. However, whether these findings are related to eating disorders or are rather reflecting the pathophysiology of borderline personality traits in these patients is still unknown. Platelet MAO activity and comorbid personality disorders were investigated in 72 patients with different subtypes of eating disorders (ED) and in a group of 28 healthy controls. ED patients comprised the following subtypes: 25 anorexia nervosa (AN) restrictive, 14 AN binge eating-purging (AN b-p), 3 anorexia nervosa not otherwise specified (AN NOS) and 30 bulimia nervosa (BN). Personality disorders and traits were assessed with the Structured Interview for Personality Disorders (SCID-II), the Zanarini Rating Scale for Borderline Personality Disorder, and the Barrat Impulsiveness Scale. Platelet MAO activity was significantly lower in ED patients with comorbid borderline personality disorder (BPD) than in ED without Borderline personality disorder (BDP). Platelet MAO activity was significantly and inversely correlated with the number and severity of BPD clinical features. In the subsample of patients with binge eating-purging symptoms (AN b-p, AN NOS and BN), platelet MAO activity was significantly lower in binge-purge patients with comorbid BPD than in binge-purge patients without BPD. The whole group of eating disorders had a significantly reduced lever of platelet MAO activity compared with the control group. The results suggest that low platelet MAO activity might characterize eating disorders with comorbid borderline personality traits, reflecting greater serotonin dysfunction in these patients. The role of decreased platelet MAO as an endophenotype with specific clinical manifestations should be explored in future studies.

  5. Effect of Antrodia camphorata on Inflammatory Arterial Thrombosis-Mediated Platelet Activation: The Pivotal Role of Protein Kinase C

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    Wan-Jung Lu

    2014-01-01

    Full Text Available Antrodia camphorata is a rare Taiwanese medicinal mushroom. Antrodia camphorata extract has been reported to exhibit antioxidant, anti-inflammation, antimetastasis, and anticancer activities and plays a role in liver fibrosis, vasorelaxation, and immunomodulation. Critical vascular inflammation leads to vascular dysfunction and cardiovascular diseases, including abdominal aortic aneurysms, hypertension, and atherosclerosis. Platelet activation plays a crucial role in intravascular thrombosis, which is involved in a wide variety of cardiovascular diseases. However, the effect of Antrodia camphorata on platelet activation remains unclear. We examined the effects of Antrodia camphorata on platelet activation. In the present study, Antrodia camphorata treatment (56–224 μg/mL inhibited platelet aggregation induced by collagen, but not U46619, an analogue of thromboxane A2, thrombin, and arachidonic acid. Antrodia camphorata inhibited collagen-induced calcium (Ca2+ mobilization and phosphorylation of protein kinase C (PKC and Akt. In addition, Antrodia camphorata significantly reduced the aggregation and phosphorylation of PKC in phorbol-12, 13-dibutyrate (PDBu activated platelets. In conclusion, Antrodia camphorata may inhibit platelet activation by inhibiting of Ca2+ and PKC cascade and the Akt pathway. Our study suggests that Antrodia camphorata may be a potential therapeutic agent for preventing or treating thromboembolic disorders.

  6. Relationship of plasma levels of LP-PLA2, GMP, LPA and platelet activation markers with transient ischemic attack

    Institute of Scientific and Technical Information of China (English)

    Hang Li

    2015-01-01

    Objective:To explore the relationship of plasma levels of LP-PLA2, GMP, LPA and platelet activation markers with transient ischemic attack(TIA).Methods:A total of 87 cases with TIA were collected, and all patients were treated with ozagrel (120mg/times/day for 2 weeks). Fasting blood were collected in 24 h after attack and 7d, 14 days after treatment respectively, then flow cytometry was used to detect indicators of platelet activation, such as CD63, PAC-1, GPⅡb /Ⅲa, and the plasma levels of LP-PLA2, GMP, LPA. The dynamic changes of the such indexes and the differences between different populations were analyzed.Results:The plasma levels of LP-PLA2, GMP, LPA and the platelet activation indexes including CD63, PAC-1, GPⅡb/Ⅲa of patients with TIA were all significantly higher than control group (allP<0.05). One day after treatment of sodium Ozagrel, the plasma levels of LP-PLA2, GMP, LPA and the platelet activation indexes such as CD63, PAC-1, GPⅡb/Ⅲa of patients with TIA began to decline, and returned to normal in the treatment of 7 d or 14 d.Conclusions:Platelet activation plays an important role in the occurrence of TIA, and antiplatelet therapy can effectively inhibit platelet activation, which has positive significance in the treatment of TIA.

  7. Altered E-NTPDase/E-ADA activities and CD39 expression in platelets of sickle cell anemia patients.

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    Castilhos, Lívia G; Doleski, Pedro H; Adefegha, Stephen A; Becker, Lara V; Ruchel, Jader B; Leal, Daniela B R

    2016-04-01

    Sickle cell anemia (SCA) is a hemoglobinopathy characterized by hemolysis and vaso-occlusions caused by rigidly distorted red blood cells. Sickle cell crisis is associated with extracellular release of nucleotides and platelets, which are critical mediators of hemostasis participating actively in purinergic thromboregulatory enzymes system.This study aimed to investigate the activities of purinergic system ecto-enzymes present on the platelet surface as well as CD39 and CD73 expressions on platelets of SCA treated patients. Fifteen SCA treated patients and 30 health subjects (control group) were selected. Ecto-nucleoside triphosphate diphosphohydrolase (E-NTPDase), ecto-5'-nucleotidase (E-5'-NT) and ecto-adenosine deaminase (E-ADA) activities were measured in platelets isolated from these individuals. Results demonstrated an increase of 41 % in the E-NTPDase for ATP hydrolysis, 52% for ADP hydrolysis and 60 % in the E-ADA activity in SCA patients (P<0.05); however, a two folds decrease in the CD39 expression in platelets was observed in the same group (P<0.01). The increased E-NTPDase activity could be a compensatory mechanism associated with the low expression of CD39 in platelets. Besides, alteration of these enzymes activities suggests that the purinergic system could be involved in the thromboregulatory process in SCA patients.

  8. Platelet proteomics and its advanced application for research of blood stasis syndrome and activated blood circulation herbs of Chinese medicine.

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    Liu, Yue; Yin, Huijun; Chen, Keji

    2013-11-01

    The development of novel and efficient antiplatelet agents that have few adverse effects and methods that improve antiplatelet resistance has long been the focus of international research on the prevention and treatment of cardiovascular and cerebrovascular diseases. Recent advances in platelet proteomics have provided a technology platform for high-quality research of platelet pathophysiology and the development of new antiplatelet drugs. The study of blood stasis syndrome (BSS) and activated blood circulation of traditional Chinese medicine (TCM) is one of the most active fields where the integration of TCM and western medicine in China has been successful. Activated blood circulation herbs (ABC herbs) of Chinese medicine are often used in the treatment of BSS. Most ABC herbs have antiplatelet and anti-atherosclerosis activity, but knowledge about their targets is lacking. Coronary heart disease (CHD), BSS, and platelet activation are closely related. By screening and identifying activated platelet proteins that are differentially expressed in BSS of CHD, platelet proteomics has helped researchers interpret the antiplatelet mechanism of action of ABC herbs and provided many potential biomarkers for BSS that could be used to evaluate the clinical curative effect of new antiplatelet drugs. In this article the progress of platelet proteomics and its advanced application for research of BSS and ABC herbs of Chinese medicine are reviewed.

  9. Effects of hormones on platelet aggregation.

    Science.gov (United States)

    Farré, Antonio López; Modrego, Javier; Zamorano-León, José J

    2014-04-01

    Platelets and their activation/inhibition mechanisms play a central role in haemostasis. It is well known agonists and antagonists of platelet activation; however, during the last years novel evidences of hormone effects on platelet activation have been reported. Platelet functionality may be modulated by the interaction between different hormones and their platelet receptors, contributing to sex differences in platelet function and even in platelet-mediated vascular damage. It has suggested aspects that apparently are well established should be reviewed. Hormones effects on platelet activity are included among them. This article tries to review knowledge about the involvement of hormones in platelet biology and activity.

  10. GPVI and GPIbα mediate staphylococcal superantigen-like protein 5 (SSL5 induced platelet activation and direct toward glycans as potential inhibitors.

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    Houyuan Hu

    Full Text Available BACKGROUND: Staphylococcus aureus (S. aureus is a common pathogen capable of causing life-threatening infections. Staphylococcal superantigen-like protein 5 (SSL5 has recently been shown to bind to platelet glycoproteins and induce platelet activation. This study investigates further the interaction between SSL5 and platelet glycoproteins. Moreover, using a glycan discovery approach, we aim to identify potential glycans to therapeutically target this interaction and prevent SSL5-induced effects. METHODOLOGY/PRINCIPAL FINDINGS: In addition to platelet activation experiments, flow cytometry, immunoprecipitation, surface plasmon resonance and a glycan binding array, were used to identify specific SSL5 binding regions and mediators. We independently confirm SSL5 to interact with platelets via GPIbα and identify the sulphated-tyrosine residues as an important region for SSL5 binding. We also identify the novel direct interaction between SSL5 and the platelet collagen receptor GPVI. Together, these receptors offer one mechanistic explanation for the unique functional influences SSL5 exerts on platelets. A role for specific families of platelet glycans in mediating SSL5-platelet interactions was also discovered and used to identify and demonstrate effectiveness of potential glycan based inhibitors in vitro. CONCLUSIONS/SIGNIFICANCE: These findings further elucidate the functional interactions between SSL5 and platelets, including the novel finding of a role for the GPVI receptor. We demonstrate efficacy of possible glycan-based approaches to inhibit the SSL5-induced platelet activation. Our data warrant further work to prove SSL5-platelet effects in vivo.

  11. Impact of prostaglandin glaucoma drops on platelet-activating factor action: an in vitro study

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    Moschos MM

    2016-12-01

    Full Text Available Marilita M Moschos,1 Eirini Nitoda,1 Irini P Chatziralli,1 Georgios D Panos,2 Constantinos A Demopoulos3 11st Department of Ophthalmology, Medical School, National and Kapodistrian University of Athens, Athens, Greece; 2Department of Ophthalmology, Geneva University Hospitals (HUG, University of Geneva, Geneva, Switzerland; 3Laboratory of Biochemistry, National and Kapodistrian University of Athens, Athens, Greece Aim: The aim of this study was to investigate the effect of different prostaglandin analogs on platelet-activating factor (PAF levels.Methods: Three prostaglandin analogs were selected: bimatoprost 0.3 mg/mL, latanoprost 50 µg/mL, and tafluprost 15 µg/mL. Each drug sample was tested for its ability to cause platelet aggregation, which was measured as PAF-induced aggregation, before and after the addition of various concentrations of the examined sample, creating a linear curve of percentage inhibition (ranging from 0% to 100% versus different concentrations of the sample. The concentration of the sample that inhibited 50% PAF-induced aggregation was calculated based on this curve, and this value was defined as IC50. In addition, the effect of eye drops on PAF metabolism was examined, through an in vitro analysis on PAF basic metabolic enzymes (PAF-cholinephosphotransferase, PAF-acetyl-CoA:1-O-alkyl-sn-glycero-3-phosphocholine acetyltransferase, and PAF-acetylhydrolase.Results: The IC50 values for Lumigan UD® (bimatoprost 0.3 mg/mL, Monoprost® (latanoprost 50 µg/mL, and Saflutan (tafluprost 15 µg/mL were 8.7, 0.28, and 1.4 µg/mL, respectively.Discussion: All three prostaglandin analogs suspended PAF, but bimatoprost induced the most potent inhibition, compared to tafluprost and to the weak effect of latanoprost. Keywords: glaucoma, platelet-activating factor, prostaglandin analogs, treatment, platelet aggregation

  12. Phage-Derived Protein Induces Increased Platelet Activation and Is Associated with Mortality in Patients with Invasive Pneumococcal Disease

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    Rahajeng N. Tunjungputri

    2017-01-01

    Full Text Available To improve our understanding about the severity of invasive pneumococcal disease (IPD, we investigated the association between the genotype of Streptococcus pneumoniae and disease outcomes for 349 bacteremic patients. A pneumococcal genome-wide association study (GWAS demonstrated a strong correlation between 30-day mortality and the presence of the phage-derived gene pblB, encoding a platelet-binding protein whose effects on platelet activation were previously unknown. Platelets are increasingly recognized as key players of the innate immune system, and in sepsis, excessive platelet activation contributes to microvascular obstruction, tissue hypoperfusion, and finally multiorgan failure, leading to mortality. Our in vitro studies revealed that pblB expression was induced by fluoroquinolones but not by the beta-lactam antibiotic penicillin G. Subsequently, we determined pblB induction and platelet activation by incubating whole blood with the wild type or a pblB knockout mutant in the presence or absence of antibiotics commonly administered to our patient cohort. pblB-dependent enhancement of platelet activation, as measured by increased expression of the α-granule protein P-selectin, the binding of fibrinogen to the activated αIIbβ3 receptor, and the formation of platelet-monocyte complex occurred irrespective of antibiotic exposure. In conclusion, the presence of pblB on the pneumococcal chromosome potentially leads to increased mortality in patients with an invasive S. pneumoniae infection, which may be explained by enhanced platelet activation. This study highlights the clinical utility of a bacterial GWAS, followed by functional characterization, to identify bacterial factors involved in disease severity.

  13. Phage-Derived Protein Induces Increased Platelet Activation and Is Associated with Mortality in Patients with Invasive Pneumococcal Disease

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    Cremers, Amelieke J.; van der Gaast-de Jongh, Christa E.; Ferwerda, Gerben; Meis, Jacques F.; Roeleveld, Nel; Bentley, Stephen D.; Pastura, Alexander S.; van Hijum, Sacha A. F. T.; van der Ven, Andre J.; de Mast, Quirijn; Zomer, Aldert

    2017-01-01

    ABSTRACT To improve our understanding about the severity of invasive pneumococcal disease (IPD), we investigated the association between the genotype of Streptococcus pneumoniae and disease outcomes for 349 bacteremic patients. A pneumococcal genome-wide association study (GWAS) demonstrated a strong correlation between 30-day mortality and the presence of the phage-derived gene pblB, encoding a platelet-binding protein whose effects on platelet activation were previously unknown. Platelets are increasingly recognized as key players of the innate immune system, and in sepsis, excessive platelet activation contributes to microvascular obstruction, tissue hypoperfusion, and finally multiorgan failure, leading to mortality. Our in vitro studies revealed that pblB expression was induced by fluoroquinolones but not by the beta-lactam antibiotic penicillin G. Subsequently, we determined pblB induction and platelet activation by incubating whole blood with the wild type or a pblB knockout mutant in the presence or absence of antibiotics commonly administered to our patient cohort. pblB-dependent enhancement of platelet activation, as measured by increased expression of the α-granule protein P-selectin, the binding of fibrinogen to the activated αIIbβ3 receptor, and the formation of platelet-monocyte complex occurred irrespective of antibiotic exposure. In conclusion, the presence of pblB on the pneumococcal chromosome potentially leads to increased mortality in patients with an invasive S. pneumoniae infection, which may be explained by enhanced platelet activation. This study highlights the clinical utility of a bacterial GWAS, followed by functional characterization, to identify bacterial factors involved in disease severity. PMID:28096486

  14. Rapid Upregulation of Orai1 Abundance in the Plasma Membrane of Platelets Following Activation with Thrombin and Collagen Related Peptide

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    Guilai Liu

    2015-11-01

    Full Text Available Background: Blood platelets accomplish primary hemostasis following vascular injury and contribute to the orchestration of occlusive vascular disease. Platelets are activated by an increase of cytosolic Ca2+-activity ([Ca2+]i, which is accomplished by Ca2+-release from intracellular stores and subsequent store operated Ca2+ entry (SOCE through Ca2+ release activated Ca2+ channel moiety Orai1. Powerful activators of platelets include thrombin and collagen related peptide (CRP, which are in part effective by activation of small G- protein Rac1. The present study explored the influence of thrombin and CRP on Orai1 protein abundance and cytosolic Ca2+-activity ([Ca2+]i in platelets drawn from wild type mice. Methods: Orai1 protein surface abundance was quantified utilizing CF™488A conjugated antibodies, and [Ca2+]i was determined with Fluo3-fluorescence. Results: In resting platelets, Orai1 protein abundance and [Ca2+]i were low. Thrombin (0.02 U/ml and CRP (5ug/ml within 2 min increased [Ca2+]i and Orai1 protein abundance at the platelet surface. [Ca2+]i was further increased by Ca2+ ionophore ionomycin (1 µM and by store depletion with the sarcoendoplasmatic Ca2+ ATPase inhibitor thapsigargin (1 µM. However, Orai1 protein abundance at the platelet surface was not significantly affected by ionomycin and only slightly increased by thapsigargin. The effect of thrombin and CRP on Orai1 abundance and [Ca2+]i was significantly blunted by Rac1 inhibitor NSC23766 (50 µM. Conclusion: The increase of [Ca2+]i following stimulation of platelets with thrombin and collagen related peptide is potentiated by ultrarapid Rac1 sensitive translocation of Orai1 into the cell membrane.

  15. Integrin αIIb-mediated PI3K/Akt activation in platelets.

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    Haixia Niu

    Full Text Available Integrin αIIbβ3 mediated bidirectional signaling plays a critical role in thrombosis and haemostasis. Signaling mediated by the β3 subunit has been extensively studied, but αIIb mediated signaling has not been characterized. Previously, we reported that platelet granule secretion and TxA2 production induced by αIIb mediated outside-in signaling is negatively regulated by the β3 cytoplasmic domain residues R(724KEFAKFEEER(734. In this study, we identified part of the signaling pathway utilized by αIIb mediated outside-in signaling. Platelets from humans and gene deficient mice, and genetically modified CHO cells as well as a variety of kinase inhibitors were used for this work. We found that aggregation of TxA2 production and granule secretion by β3Δ724 human platelets initiated by αIIb mediated outside-in signaling was inhibited by the Src family kinase inhibitor PP2 and the PI3K inhibitor wortmannin, respectively, but not by the MAPK inhibitor U0126. Also, PP2 and wortmannin, and the palmitoylated β3 peptide R(724KEFAKFEEER(734, each inhibited the phosphorylation of Akt residue Ser473 and prevented TxA2 production and storage granule secretion. Similarly, Akt phosphorylation in mouse platelets stimulated by the PAR4 agonist peptide AYPGKF was αIIbβ3-dependent, and blocked by PP2, wortmannin and the palmitoylated peptide p-RKEFAKFEEER. Akt was also phosphorylated in response to mAb D3 plus Fg treatment of CHO cells in suspension expressing αIIbβ3-Δ724 or αIIbβ3E(724AERKFERKFE(734, but not in cells expressing wild type αIIbβ3. In summary, SFK(s and PI3K/Akt signaling is utilized by αIIb-mediated outside-in signaling to activate platelets even in the absence of all but 8 membrane proximal residues of the β3 cytoplasmic domain. Our results provide new insight into the signaling pathway used by αIIb-mediated outside-in signaling in platelets.

  16. Piperine Inhibits the Activities of Platelet Cytosolic Phospholipase A2 and Thromboxane A2 Synthase without Affecting Cyclooxygenase-1 Activity: Different Mechanisms of Action Are Involved in the Inhibition of Platelet Aggregation and Macrophage Inflammatory Response

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    Dong Ju Son

    2014-08-01

    Full Text Available PURPOSE: Piperine, a major alkaloid of black pepper (Piper nigrum and long pepper (Piper longum, was shown to have anti-inflammatory activity through the suppression of cyclooxygenase (COX-2 gene expression and enzyme activity. It is also reported to exhibit anti-platelet activity, but the mechanism underlying this action remains unknown. In this study, we investigated a putative anti-platelet aggregation mechanism involving arachidonic acid (AA metabolism and how this compares with the mechanism by which it inhibits macrophage inflammatory responses; METHODS: Rabbit platelets and murine macrophage RAW264.7 cells were treated with piperine, and the effect of piperine on the activity of AA-metabolizing enzymes, including cytosolic phospholipase A2 (cPLA2, COX-1, COX-2, and thromboxane A2 (TXA2 synthase, as well as its effect on AA liberation from the plasma membrane components, were assessed using isotopic labeling methods and enzyme immunoassay kit; RESULTS: Piperine significantly suppressed AA liberation by attenuating cPLA2 activity in collagen-stimulated platelets. It also significantly inhibited the activity of TXA2 synthase, but not of COX-1, in platelets. These results suggest that piperine inhibits platelet aggregation by attenuating cPLA2 and TXA2 synthase activities, rather than through the inhibition of COX-1 activity. On the other hand, piperine significantly inhibited lipopolysaccharide-induced generation of prostaglandin (PGE2 and PGD2 in RAW264.7 cells by suppressing the activity of COX-2, without effect on cPLA2; CONCLUSION: Our findings indicate that piperine inhibits platelet aggregation and macrophage inflammatory response by different mechanisms.

  17. Statin and Aspirin Pretreatment Are Associated with Lower Neurological Deterioration and Platelet Activity in Patients with Acute Ischemic Stroke.

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    Yi, Xingyang; Han, Zhao; Wang, Chun; Zhou, Qiang; Lin, Jing

    2017-02-01

    Aspirin and statin are recommended for the treatment of acute ischemic stroke. However, whether aspirin and statin pretreatment is associated with clinical outcomes has not been well addressed. This study aimed to evaluate the effect of pre-existing statin and aspirin use on platelet activation and clinical outcome in acute ischemic stroke patients. We conducted a prospective, multicenter observational study in patients with acute ischemic stroke. Platelet aggregation and platelet-leukocyte aggregates were measured on admission and during 7-10 days after admission. The primary outcome of the study was neurological deterioration (ND) within 10 days after admission. The secondary outcome was a composite of recurrent ischemic stroke, myocardial infarction, and death during the first 3 months after admission. Physical disability was evaluated using the modified Rankin Scale score at 3 months after admission. Among 1124 enrolled patients, 270 (24%) experienced ND. Higher platelet aggregation and platelet-leukocyte aggregates on admission and during 7-10 days were associated with ND. Platelet aggregation and platelet-leukocyte aggregates on admission were significantly lower in the patients with pre-existing statin or aspirin use than those without treatment. Patients with prestroke concomitant statin and aspirin treatment had significantly lower incidence of ND than those without treatment. Diabetes mellitus, fasting glucose, platelet-leukocyte aggregates, and prestroke concomitant statin and aspirin use were independently associated with ND. Prestroke concomitant statin and aspirin use is associated with lower neurological deterioration and platelet activity in patients with acute ischemic stroke. Copyright © 2017 National Stroke Association. Published by Elsevier Inc. All rights reserved.

  18. Platelet-activating factor induces phospholipid turnover, calcium flux, arachidonic acid liberation, eicosanoid generation, and oncogene expression in a human B cell line

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    Schulam, P.G.; Kuruvilla, A.; Putcha, G.; Mangus, L.; Franklin-Johnson, J.; Shearer, W.T. (Baylor College of Medicine, Houston, TX (USA))

    1991-03-01

    Platelet-activating factor is a potent mediator of the inflammatory response. Studies of the actions of platelet-activating factor have centered mainly around neutrophils, monocytes, and platelets. In this report we begin to uncover the influence of platelet-activating factor on B lymphocytes. Employing the EBV-transformed human B cell line SKW6.4, we demonstrate that platelet-activating factor significantly alters membrane phospholipid metabolism indicated by the incorporation of 32P into phosphatidylcholine, phosphatidylinositol, and phosphatidic acid but not significantly into phosphatidylethanolamine at concentrations ranging from 10(-9) to 10(-6) M. The inactive precursor, lyso-platelet-activating factor, at a concentration as high as 10(-7) M had no effect on any of the membrane phospholipids. We also show that platelet-activating factor from 10(-12) to 10(-6) M induced rapid and significant elevation in intracellular calcium levels, whereas lyso-platelet-activating factor was again ineffective. We further demonstrate the impact of platelet-activating factor binding to B cells by measuring platelet-activating factor induced arachidonic acid release and 5-hydroxyeicosatetraenoic acid production. Moreover, platelet-activating factor was capable of inducing transcription of the nuclear proto-oncogenes c-fos and c-jun. Finally we explored the possible role of 5-hydroxyeicosatetraenoic acid as a regulator of arachidonic acid liberation demonstrating that endogenous 5-lipoxygenase activity modulates platelet-activating factor induced arachidonic acid release perhaps acting at the level of phospholipase A2. In summary, platelet-activating factor is shown here to have a direct and profound effect on a pure B cell line.

  19. The effect of clopidogrel on platelet activity in patients with and without type-2 diabetes mellitus: a comparative study.

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    Schuette, Claudia; Steffens, Daniel; Witkowski, Marco; Stellbaum, Caroline; Bobbert, Peter; Schultheiss, Heinz-Peter; Rauch, Ursula

    2015-02-03

    Although antiplatelet therapy involving clopidogrel is a standard treatment for preventing cardiovascular events after coronary stent implantation, patients can display differential responses. Here, we assessed the effectiveness of clopidogrel on platelet function inhibition in subjects with and without type-2 diabetes and stable coronary artery disease. In addition, we investigated the correlation between platelet function and routine clinical parameters. A total of 64 patients with stable coronary heart disease were enrolled in the study. Among these, 32 had known type-2 diabetes, whereas the remaining 32 subjects were non-diabetics (control group). A loading dose of 300 mg clopidogrel was given to clopidogrel-naïve patients (13 patients in the diabetes group and 14 control patients). All patients were given a daily maintenance dose of 75 mg clopidogrel. In addition, all patients received 100 mg ASA per day. Agonist-induced platelet aggregation measurements were performed on hirudin-anticoagulated blood using an impedance aggregometer (Multiple Platelet Function Analyzer, Dynabyte, Munich, Germany). Blood samples were drawn from the antecubital vein 24 h after coronary angiography with percutaneous coronary intervention. The platelets were then stimulated with ADP alone or ADP and prostaglandin-E (ADP and ADP-PGE tests, respectively) in order to evaluate clopidogrel-mediated inhibition of platelet function. The effectiveness of ASA was measured by stimulation with arachidonic acid (ASPI test). In addition, maximal platelet aggregation was assessed via stimulation with thrombin receptor-activating peptide (TRAP test). Patients with diabetes exhibited significantly less inhibition of platelet function than patients without diabetes (ADP-PGE test p = 0.003; ASPI test p = 0.022). Administering a clopidogrel loading dose of 300 mg did not result in a lower level of ADP-PGE-induced platelet reactivity in comparison to the use of a 75 mg maintenance dose

  20. Thrombin Receptor-Activating Protein (TRAP-Activated Akt Is Involved in the Release of Phosphorylated-HSP27 (HSPB1 from Platelets in DM Patients

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    Haruhiko Tokuda

    2016-05-01

    Full Text Available It is generally known that heat shock protein 27 (HSP27 is phosphorylated through p38 mitogen-activated protein (MAP kinase. We have previously reported that HSP27 is released from human platelets associated with collagen-induced phosphorylation. In the present study, we conducted an investigation into the effect of thrombin receptor-activating protein (TRAP on the release of HSP27 in platelets in type 2 diabetes mellitus (DM patients. The phosphorylated-HSP27 levels induced by TRAP were directly proportional to the aggregation of platelets. The levels of phosphorylated-HSP27 (Ser-78 were correlated with the levels of phosphorylated-p38 MAP kinase and phosphorylated-Akt in the platelets stimulated by 10 µM TRAP but not with those of phosphorylated-p44/p42 MAP kinase. The levels of HSP27 released from the TRAP (10 µM-stimulated platelets were correlated with the levels of phosphorylated-HSP27 in the platelets. The released platelet-derived growth factor-AB (PDGF-AB levels were in parallel with the HSP27 levels released from the platelets stimulated by 10 µM TRAP. Although the area under the curve (AUC of small aggregates (9–25 µm induced by 10 µM TRAP showed no significant correlation with the released HSP27 levels, AUC of medium aggregates (25–50 µm, large aggregates (50–70 µm and light transmittance were significantly correlated with the released HSP27 levels. TRAP-induced phosphorylation of HSP27 was truly suppressed by deguelin, an inhibitor of Akt, in the platelets from a healthy subject. These results strongly suggest that TRAP-induced activation of Akt in addition to p38 MAP kinase positively regulates the release of phosphorylated-HSP27 from human platelets, which is closely related to the platelet hyper-aggregation in type 2 DM patients.

  1. Methylglyoxal induces platelet hyperaggregation and reduces thrombus stability by activating PKC and inhibiting PI3K/Akt pathway.

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    Karin Hadas

    Full Text Available Diabetes is characterized by a dysregulation of glucose homeostasis and platelets from patients with diabetes are known to be hyper-reactive and contribute to the accelerated development of vascular diseases. Since many of the deleterious effects of glucose have been attributed to its metabolite methylgyloxal (MG rather than to hyperglycemia itself, the aim of the present study was to characterize the effects of MG on platelet function. Washed human platelets were pre-incubated for 15 min with MG and platelet aggregation, adhesion on matrix-coated slides and signaling (Western blot were assessed ex vivo. In vivo, the effect of MG on thrombus formation was determined using the FeCl3-induced carotid artery injury model. MG potentiated thrombin-induced platelet aggregation and dense granule release, but inhibited platelet spreading on fibronectin and collagen. In vivo, MG accelerated thrombus formation but decreased thrombus stability. At the molecular level, MG increased intracellular Ca(2+ and activated classical PKCs at the same time as inhibiting PI3K/Akt and the β3-integrin outside-in signaling. In conclusion, these findings indicate that the enhanced MG concentration measured in diabetic patients can directly contribute to the platelet dysfunction associated with diabetes characterized by hyperaggregability and reduced thrombus stability.

  2. Methylglyoxal induces platelet hyperaggregation and reduces thrombus stability by activating PKC and inhibiting PI3K/Akt pathway.

    Science.gov (United States)

    Hadas, Karin; Randriamboavonjy, Voahanginirina; Elgheznawy, Amro; Mann, Alexander; Fleming, Ingrid

    2013-01-01

    Diabetes is characterized by a dysregulation of glucose homeostasis and platelets from patients with diabetes are known to be hyper-reactive and contribute to the accelerated development of vascular diseases. Since many of the deleterious effects of glucose have been attributed to its metabolite methylgyloxal (MG) rather than to hyperglycemia itself, the aim of the present study was to characterize the effects of MG on platelet function. Washed human platelets were pre-incubated for 15 min with MG and platelet aggregation, adhesion on matrix-coated slides and signaling (Western blot) were assessed ex vivo. In vivo, the effect of MG on thrombus formation was determined using the FeCl3-induced carotid artery injury model. MG potentiated thrombin-induced platelet aggregation and dense granule release, but inhibited platelet spreading on fibronectin and collagen. In vivo, MG accelerated thrombus formation but decreased thrombus stability. At the molecular level, MG increased intracellular Ca(2+) and activated classical PKCs at the same time as inhibiting PI3K/Akt and the β3-integrin outside-in signaling. In conclusion, these findings indicate that the enhanced MG concentration measured in diabetic patients can directly contribute to the platelet dysfunction associated with diabetes characterized by hyperaggregability and reduced thrombus stability.

  3. Platelet-activating factor in liver injury: A relational scope

    Institute of Scientific and Technical Information of China (English)

    Nikolaos P Karidis; Gregory Kouraklis; Stamatios E Theocharis

    2006-01-01

    The hepatocyte, the main cellular component of the liver, exhibits variable susceptibility to different types of injury induced by endogenous or exogenous factors.Hepatocellular dysfunction or death and regeneration are dependent upon the complicated interactions between numerous biologically active molecules. Plateletactivating factor (PAF) seems to play a pivotal role as the key mediator of liver injury in the clinical and experimental setting, as implied by the beneficial effects of its receptor antagonists. A comprehensive up-todate overview of the specific functional and regulatory properties of PAF in conditions associated with liver injury is attempted in this review.

  4. Platelets and hemostasis

    Directory of Open Access Journals (Sweden)

    M. A. Panteleev

    2014-09-01

    Full Text Available Platelets are anuclear cell fragments playing important role in hemostasis, termination of bleeding after damage, as well as in pathological thrombus formation. The main action of platelets is the formation of aggregates, overlapping the injury. They obtained the ability to aggregate by the transition process called activation. Despite the relatively simple and definite function platelet structure is very difficult: they have almost a full set of organelles, including the endoplasmic reticulum, mitochondria and other entities. When activated platelets secrete various granules interact with plasma proteins and red blood cells and other tissues. Their activation is controlled by multiple receptors and complex signaling cascades. In this review platelet structure, mechanisms of its functioning in health and disease, diagnostic methods of platelet function and approaches to their correction were considered. Particular attention will be given to those areas of the science of platelets, which still lay hidden mysteries.

  5. A whole blood flow cytometric determination of platelet activation by unfractionated and low molecular weight heparin in vitro.

    Science.gov (United States)

    Klein, Bernd; Faridi, Andreé; von Tempelhoff, G F; Heilmann, Lothar; Mittermayer, Christian; Rath, Werner

    2002-12-15

    The influence of unfractionated (Heparin-Natrium) and low-molecular heparin (Fragmin(R)) on platelet activation in whole blood was investigated by FACS analysis in vitro using antibodies against glycoprotein (gp) IIb/IIIa (CD 41), GMP 140 (CD 62P), gp 53 (CD 63) and fibrinogen. Samples were also labeled with anti-gp Ib (CD 42b). Neither unfractionated heparin (UFH) nor low molecular weight heparin (LMWH) led to significant (i.e., p<0.05) changes in fluorescence intensities of platelets labeled with anti-gp IIb/IIIa or anti-gp 53. Significant platelet activation due to unfractionated heparin could be observed by labeling with anti-GMP 140 (UFH: p=0.009; LMWH: p=0.16). The proportion of platelets with surface-bound fibrinogen was significantly increased (UFH: p=0.00006; LMWH: p=0.008). After incubation with heparins, activation ability of platelets by adenosine diphosphate (ADP) was significantly increased. The potentiating action of unfractionated heparin was larger. Therefore, flow cytometric results of platelet activation in patients receiving heparin should be interpreted carefully.

  6. Hematopoietic lineage cell specific protein 1 (HS1) is a functionally important signaling molecule in platelet activation.

    Science.gov (United States)

    Kahner, Bryan N; Dorsam, Robert T; Mada, Sripal R; Kim, Soochong; Stalker, Timothy J; Brass, Lawrence F; Daniel, James L; Kitamura, Daisuke; Kunapuli, Satya P

    2007-10-01

    Collagen activates platelets through an intracellular signaling cascade downstream of glycoprotein VI (GPVI). We have investigated the contribution of hematopoietic lineage cell-specific protein 1 (HS1) downstream of GPVI in platelet activation. Stimulation of GPVI leads to tyrosine phosphorylation of HS1, which is blocked by Src-family kinase inhibitors. Coimmunoprecipitation experiments revealed that HS1 associates with Syk and phosphatidylinositol 3-kinases. HS1-null mice displayed increased bleeding times and increased time to occlusion in the FeCl(3) in vivo thrombosis model compared with their wild-type littermates. In addition, aggregation and secretion responses were diminished in HS1-null mouse platelets after stimulation of GPVI and protease-activated receptor 4 (PAR-4) agonists compared with wild-type littermate mouse platelets. Finally, Akt phosphorylation was diminished after GPVI or PAR-4 stimulation in platelets from HS1-null mice compared with their wild-type littermates. These results demonstrate that phosphorylation of the HS1 protein occurs downstream of GPVI stimulation and that HS1 plays a significant functional role in platelet activation downstream of GPVI and PARs.

  7. Adenylate-cyclase activity in platelets of patients with obsessive-compulsive disorder

    Directory of Open Access Journals (Sweden)

    D Marazziti, S Baroni

    2009-07-01

    Full Text Available D Marazziti, S Baroni, L Palego, I Masala, G Consoli, M Catena Dell’Osso, G Giannaccini, A LucacchiniDipartimento di Psichiatria, Neurobiologia, Farmacologia e Biotecnologie, Università di Pisa, Pisa, ItalyAbstract: Although the main biological hypothesis on the pathophysiology of obsessive-compulsive disorder (OCD is centered on the serotonin system, indications are available that other neurotransmitters, and even second messengers, particularly the cyclic adenosine monophosphate (cAMP signaling, may be involved, though effective data are few. Therefore, the aim of the present study was to evaluate and compare the basal and isoprenaline (ISO-stimulated velocity of adenylate-cyclase (AC in human platelet membranes of patients with OCD and healthy control subjects. The results showed that the basal and ISO-stimulated AC activity, as well as the dose-response curves of ISO by using agonist concentrations ranging between 0.1 nM and 10 µM, were not different in the two groups. However, OCD patients showed lower EC50 and higher Emax values than healthy subjects. These findings suggest the presence of supersensitive β-adrenergic receptors in platelets of OCD patients.Keywords: obsessive-compulsive disorder, norepinephrine, second messengers, adenylate-cyclase, platelets, isoprenaline, β-adrenergic receptors

  8. Ultrastructural characteristics of fibrin clots from canine and feline platelet concentrates activated with calcium gluconate or calcium gluconate plus batroxobin

    OpenAIRE

    Silva, Raúl F; Carmona, Jorge U; Rezende, Cleuza MF

    2013-01-01

    Background The aim of this study was to use transmission electron microscopy to describe the ultrastructural characteristics of clots obtained from canine and feline platelet concentrates (PC) that had been activated with calcium gluconate (CG) or CG plus batroxobin (CGB). Platelets from fibrin clots were classified according their morphological changes. The area of the intercellular space (μm2), the area of the fibrin fibers (μm2), and the width of the fibrin fibers (μm) were determined for ...

  9. Activation of tumour cell ECM degradation by thrombin-activated platelet membranes: potentially a P-selectin and GPIIb/IIIa-dependent process.

    Science.gov (United States)

    Pang, J H; Coupland, L A; Freeman, C; Chong, B H; Parish, Christopher R

    2015-06-01

    The promotion of tumour metastasis by platelets may occur through several mechanisms including the induction of a more metastatic phenotype in tumour cells and assisted extravasation of circulating tumour cells. Whilst the mechanisms underlying platelet-assisted extravasation have been extensively studied, much less attention has been paid to the mechanisms underlying platelet promotion of an aggressive phenotype within a tumour cell population. Herein, we demonstrate in vitro that MDA-MB-231 breast carcinoma cells incubated with washed thrombin-activated platelet membranes adopt a Matrigel-degrading phenotype in a dose- and contact time-dependent manner. The same phenotypic change was observed with three other human tumour cell lines of diverse anatomical origin. Moreover, tumour cell lines that had been cultured with washed thrombin-activated platelet membranes had a greater metastatic capacity when injected into mice. This in vivo effect was reliant upon a co-incubation period of >2 h implying a mechanism involving more than platelet membrane binding that occurred within 5 min. Upon further investigation it was found that simultaneous blocking of the platelet-membrane proteins P-selectin and GPIIb/IIIa prevented interactions between platelet membranes and MDA-MB-231 cells but also significantly reduced the ability of tumour cells to degrade Matrigel. These results confirm that platelets induce a more aggressive phenotype in tumour cells but also identify the platelet proteins involved in this effect. P-selectin and GPIIb/IIIa also play a role in assisting tumour cell extravasation and, thus, are ideal targets for the therapeutic intervention of both stages of platelet-assisted metastasis.

  10. Role of platelet-activating factor in reproduction:sperm function

    Institute of Scientific and Technical Information of China (English)

    William E. Roudebush

    2001-01-01

    Since its discovery nearly thirty years ago, platelet-activating factor has emerged as one of the more important lipid mediators known. Platelet-activating factor (PAF; 1- O-alkyl-2- O-acetyl-sn-glycero-3-phosphorylcholine) exists en dogenously as a mixture of molecular species with structural variants of the alkyl moiety. PAF is a novel potent signal ing phospholipid that has unique pleiotropic biological properties in addition to platelet activation. PAF also plays a sig nificant role in reproduction. PAF content in squirrel monkey sperm is significantly higher during the breeding season than the non-breeding season. PAF content in human sperm has a positive correlation with seminal parameters and preg nancy outcomes. High-fertility boars have significantly more PAF in their sperm than low-fertility boars. The enzymes (lyso-PAF-acetyltransferase and PAF-acetylhydrolase) necessary for PAF activation and deactivation are present in sperm. PAF-acetylhydrolase may act as a "decapacitation factor". Removal of this enzyme during capacitation may promote PAF synthesis increasing motility and fertilization. PAF also plays a significant role in the fertilization process,enhancing the fertilization rates of oocytes. Enhanced embryo development has also been reported in oocytes fertilized with PAF-treated sperm. PAF antagonists inhibit sperm motility, acrosome reaction, and fertilization, thus suggesting the presence of receptors for PAF. The PAF-receptor is present on sperm, with altered transcript levels and distribution patterns on abnormal cells. Whereas the exact mechanism of PAF in sperm function and reproduction is uncertain, its importance in normal fertility is substantial. The reproductive significance of PAF activity in sperm and fertility plus the role of PAF in the establishment of pregnancy requires further study.

  11. Increase in phosphotidylinositide-3 kinase activity by nitrotyrosylation of lysates of platelets from patients with systemic sclerosis.

    Science.gov (United States)

    Chiang, Thomas M; Postlethwaite, Arnold E

    2006-01-01

    We have observed that the platelet non-integrin collagen receptor (65 kDa) and another protein (M(r) 185 kDa) are altered in the posttranslational modification by nitrotyrosylation in platelets from patients with systemic sclerosis (SSc). We reported the identification of nitrotyrosylated 65-kDa proteins in a previous study. In the present investigation, using Western blots, one- and two-dimensional gel electrophoreses and matrix assisted ionization/desorption-time of flight (MALDI-TOF) we have identified the 185-kDa protein as phosphoinositide kinase C2beta (PI 3-K). There is a positive correlation between the nitrotyrosylation of PI 3-K and activity of the enzyme, i.e., the nitrotyrosylation of PI 3-K increases its enzymatic activity. In addition, the activity of PI 3-K increases in nitrotyrosylated platelet lystaes from patients with SSc compared to normal volunteer controls, suggesting that this is an alteration in the posttranslational modification of PI 3-K in platelets from patients with SSc. The increased nitrotyrosylation of PI 3-K may contribute to the impairment of platelet function in patients with SSc by increasing platelet reactivity to matrix components within the vascular walls of patients with this disease.

  12. Megakaryocytic cells synthesize and platelets secrete alpha5-laminins, and the endothelial laminin isoform laminin 10 (alpha5beta1gamma1) strongly promotes adhesion but not activation of platelets.

    Science.gov (United States)

    Nigatu, Ayele; Sime, Wondossen; Gorfu, Gezahegn; Geberhiwot, Tarekegn; Andurén, Ingegerd; Ingerpuu, Sulev; Doi, Masayuki; Tryggvason, Karl; Hjemdahl, Paul; Patarroyo, Manuel

    2006-01-01

    Following vascular injury, basement membrane (BM) components of the blood vessels are exposed to circulating cells and may contribute to hemostasis and/or thrombosis. Laminins 8 (LN-8) (alpha4beta1gamma1) and 10 (LN-10) (alpha5beta1gamma1) are major laminin isoforms of the endothelial BM, and LN-8 is also secreted by activated platelets. In the present study, we demonstrate synthesis of alpha5-laminins LN-10 and LN-11 (alpha5beta2gamma1) by megakaryocytic cells, and intracellular expression of these laminin isoforms in blood platelets. In contrast to platelet LN alpha4 chain that had an apparent molecular weight of 180 kDa and associated mostly to LNbeta1 chain, platelet LNalpha5 consisted of 300/350 kDa polypeptides and associated mainly to LNbeta2. Both alpha4- and alpha5-laminins were secreted by platelets following stimulation. When compared to recombinant human (rh) LN-8, rhLN-10 was much more adhesive to platelets, though adhesion to both proteins was largely mediated via alpha6beta1 integrin. In spite of their adhesive properties, rhLN-8 and rhLN-10 induced neither P-selectin expression nor cell aggregation, two signs of platelet activation. This study demonstrates synthesis/expression of heterotrimeric alpha5-laminins in hematopoietic/blood cells, and provides evidence for the adhesive, but not activating, role of endothelial laminin isoforms in platelet biology.

  13. Kaempferol suppresses collagen-induced platelet activation by inhibiting NADPH oxidase and protecting SHP-2 from oxidative inactivation.

    Science.gov (United States)

    Wang, Su Bin; Jang, Ji Yong; Chae, Yun Hee; Min, Ji Hyun; Baek, Jin Young; Kim, Myunghee; Park, Yunjeong; Hwang, Gwi Seo; Ryu, Jae-Sang; Chang, Tong-Shin

    2015-06-01

    Reactive oxygen species (ROS) generated upon collagen stimulation act as second messengers to propagate various platelet-activating events. Among the ROS-generating enzymes, NADPH oxidase (NOX) plays a prominent role in platelet activation. Thus, NOX has been suggested as a novel target for anti-platelet drug development. Although kaempferol has been identified as a NOX inhibitor, the influence of kaempferol on the activation of platelets and the underlying mechanism have never been investigated. Here, we studied the effects of kaempferol on NOX activation, ROS-dependent signaling pathways, and functional responses in collagen-stimulated platelets. Superoxide anion generation stimulated by collagen was significantly inhibited by kaempferol in a concentration-dependent manner. More importantly, kaempferol directly bound p47(phox), a major regulatory subunit of NOX, and significantly inhibited collagen-induced phosphorylation of p47(phox) and NOX activation. In accordance with the inhibition of NOX, ROS-dependent inactivation of SH2 domain-containing protein tyrosine phosphatase-2 (SHP-2) was potently protected by kaempferol. Subsequently, the specific tyrosine phosphorylation of key components (Syk, Vav1, Btk, and PLCγ2) of collagen receptor signaling pathways was suppressed by kaempferol. Kaempferol also attenuated downstream responses, including cytosolic calcium elevation, P-selectin surface exposure, and integrin-αIIbβ3 activation. Ultimately, kaempferol inhibited platelet aggregation and adhesion in response to collagen in vitro and prolonged in vivo thrombotic response in carotid arteries of mice. This study shows that kaempferol impairs collagen-induced platelet activation through inhibition of NOX-derived ROS production and subsequent oxidative inactivation of SHP-2. This effect suggests that kaempferol has therapeutic potential for the prevention and treatment of thrombovascular diseases.

  14. Cyclic AMP-insensitive activation of c-Src and Syk protein-tyrosine kinases through platelet membrane glycoprotein VI.

    Science.gov (United States)

    Ichinohe, T; Takayama, H; Ezumi, Y; Yanagi, S; Yamamura, H; Okuma, M

    1995-11-24

    Platelet glycoprotein (GP) VI is a so-far uncharacterized 62-kDa membrane protein, whose deficiency results in selective impairment in collagen-induced platelet aggregation. Our group previously reported a human polyclonal antibody (anti-p62 IgG) that induces activation of normal, but not of GPVI-deficient, platelets in an Fc-independent manner. The F(ab')2 fragments of this antibody (F(ab')2-anti-p62) stimulated tyrosine phosphorylation of numerous proteins, which was not prevented even in the presence of cAMP-increasing agents such as prostacyclin. Pretreatment of platelets with the protein-tyrosine kinase (PTK) inhibitor tyrphostin A47 completely abolished F(ab')2-anti-p62-induced platelet aggregation in parallel with dose-dependent inhibition of protein-tyrosine phosphorylation, indicating an essential requirement of PTK activity for generating GPVI-mediated signaling. We found that two cytosolic PTKs, c-Src and Syk, became rapidly activated in response to F(ab')2-anti-p62 in a way insensitive to elevation of cAMP. In contrast, in the presence of prostacyclin, F(ab')2-anti-p62 did not stimulate tyrosine phosphorylation of the focal adhesion kinase. cAMP-insensitive activation of c-Src and Syk was also observed in collagen but not thrombin-stimulated platelets. Moreover, either F(ab')2-anti-p62 or collagen stimulated cAMP-insensitive tyrosine phosphorylation of phospholipase C-gamma 2. These results indicate that the receptor-mediated activation of several PTKs in platelets is regulated through a cAMP-sensitive or -insensitive mechanism depending on the nature of each stimulus, and also suggest that GPVI engagement is coupled to cAMP-insensitive activation of c-Src and Syk accompanied by tyrosine phosphorylation of numerous substrates including phospholipase C-gamma 2 in a manner similar to collagen stimulation.

  15. [Experimental research on the effects of different activators on the formation of platelet-rich gel and the release of bioactive substances in human platelet-rich plasma].

    Science.gov (United States)

    Yang, Y; Zhang, W; Cheng, B

    2017-01-20

    Objective: To explore the effects of calcium gluconate and thrombin on the formation of platelet-rich gel (PRG) and the release of bioactive substances in human platelet-rich plasma (PRP) and the clinical significance. Methods: Six healthy blood donors who met the inclusion criteria were recruited in our unit from May to August in 2016. Platelet samples of each donor were collected for preparation of PRP. (1) PRP in the volume of 10 mL was collected from each donor and divided into thrombin activation group (TA, added with 0.5 mL thrombin solution in dose of 100 U/mL) and calcium gluconate activation group (CGA, added with 0.5 mL calcium gluconate solution in dose of 100 g/L) according to the random number table, with 5 mL PRP in each group. Then the PRP of the two groups was activated in water bath at 37 ℃ for 1 h. The formation time of PRG was recorded, and the formation situation of PRG was observed within 1 hour of activation. After being activated for 1 h, one part of PRG was collected to observe the distribution of fibrous protein with HE staining, and another part of PRG was collected to observe platelet ultrastructure under transmission electron microscope (TEM). After being activated for 1 h, the supernatant was collected to determine the content of transforming growth factor β(1, )platelet-derived growth factor BB (PDGF-BB), vascular endothelial growth factor, basic fibroblast growth factor (bFGF), epidermal growth factor, and insulin-like growth factorⅠby enzyme-linked immunosorbent assay. (2) Another 10 mL PRP from each donor was collected and grouped as above, and the platelet suspension was obtained after two times of centrifugation and resuspension with phosphate buffered saline, respectively. And then they were treated with corresponding activator for 1 h as that in experiment (1). Nanoparticle tracking analyzer was used to detect the concentrations of microvesicles with different diameters and total microvesicles derived from platelet. Data

  16. New organic nitrate-containing benzyloxy isonipecotanilide derivatives with vasodilatory and anti-platelet activity.

    Science.gov (United States)

    de Candia, Modesto; Marini, Elisabetta; Zaetta, Giorgia; Cellamare, Saverio; Di Stilo, Antonella; Altomare, Cosimo D

    2015-05-25

    A number of new nitric oxide (NO)-precursors were synthesized by grafting nitrate-containing moieties on the structures of the benzyloxy isonipecotanilide derivatives 1 and 2 already reported as moderately potent antiplatelet agents. Various nitrooxy (ONO2)-alkyl side chains were covalently linked to the piperidine nitrogen of the parent compounds through carbamate and amide linkage, and the synthesis of a benzyl nitrate analog (15) of compound 1 was also achieved. The in vitro vasodilatory activities, as well as platelet anti-aggregatory effects, of the newly synthesized organic nitrates were assessed. The (ONO2)methyl carbamate-based derivative 5a and the benzyl nitrate analog 15, which on the other hand retain activity as inhibitors of ADP-induced platelet aggregation, exhibited strong NO-mediated vasodilatory effects on pre-contracted rat aorta strips, with EC50 values in the low nanomolar range (13 and 29 nM, respectively). Experiments carried out with the selectively inhibited soluble guanylate cyclase (sGC), which is the key enzyme of the NO-mediated pathway leading to vascular smooth muscle relaxation, confirmed the involvement of NO in the observed vasodilation. The nitrate derivatives proved to be stable in acidic aqueous solution and at pH 7.4. In human serum, unlike 5a, which showed not to undergo enzyme-catalyzed decomposition, the other tested (ONO2)-alkyl carbamate-based compounds (5b and 5e) and benzyl nitrate 15 underwent a faster degradation. However, their decomposition rates in serum were quite slow (t½>2.6 h), which suggests that nitrate moiety is poorly metabolized in blood plasma and that much of the in vitro anti-platelet activity has to be attributed to the intact (ONO2)-containing molecules.

  17. Value research on thromboelastogram(TEG) in the monitoring of platelet activity variation tendency of PCI surgery patients

    Institute of Scientific and Technical Information of China (English)

    Xing-Bin Zou; He Huang

    2015-01-01

    Objective:To discuss the value research on thromboelastogram (TEG) in the monitoring of platelet activity variation tendency of PCI surgery patients.Method:180 cases of patients with coronary heart disease who have proceeded PCI surgery were selected and divided into AMI group, UAP group and AP group. To compare the coagulation indicator, TEG and pathological changes of these three groups; all patients were adopted conventional therapy, after operation, divided them into anti-platelet low reaction group (platelet high reaction group) and normal group according to platelet aggregation rate monitored by TEG, and compared the clotting all items, clinical indicator, PCI postoperative platelet aggregation inhibition rate and clinical ischemia cases occurrence rate within 6 months follow up visit of both groups.Results: TEG parametric R value and K value in AMI group and UAP group were obviously lower than that in AP group, MA value and angle value were obviously higher than AP group, significant difference; TEG image in AMI group and UAP group mainly featured hypercoagulability, while TEG image had no hypercoagulability in AP group; Chi-square test showed that hypercoagulability image percentage differences between these three groups had statistical significance; ADP and AA induced platelet inhibition rate determined by TEG in high reaction group was obviously lower than that in normal group; 6 cases in platelet high reaction group: CK-MB rose and exceeded normal value upper limit (10.90%), 9 cases: cTnI rose and exceeded normal value upper limit (19.6%), compared with normal group (3 cases, 2.4%; 5 cases, 4%), the value in platelet high reaction group was higher, and the difference was significant; platelet high reaction group: totally 10 cases of ischemia, occurrence rate was 10.5%, while platelet normal reaction group: totally 3 cases (2.4%), chi-square test showed that the difference between these two groups had statistical significance

  18. Antiplatelet activities of anthrax lethal toxin are associated with suppressed p42/44 and p38 mitogen-activated protein kinase pathways in the platelets.

    Science.gov (United States)

    Kau, Jyh-Hwa; Sun, Der-Shan; Tsai, Wei-Jern; Shyu, Huey-Fen; Huang, Hsin-Hsien; Lin, Hung-Chi; Chang, Hsin-Hou

    2005-10-15

    Anthrax lethal toxin (LT) is the major virulence factor produced by Bacillus anthracis, but the mechanism by which it induces high mortality remains unclear. We found that LT treatment could induce severe hemorrhage in mice and significantly suppress human whole-blood clotting and platelet aggregation in vitro. In addition, LT could inhibit agonist-induced platelet surface P-selectin expression, resulting in the inhibition of platelet-endothelial cell engagements. Data from Western blot analysis indicated that LT treatment resulted in the suppression of p42/44 and p38 mitogen-activated protein kinase pathways in platelets. Combined treatments with LT and antiplatelet agents such as aspirin and the RGD-containing disintegrin rhodostomin significantly increased mortality in mice. Our data suggest that platelets are a pathogenic target for anthrax LT.

  19. Whole blood coagulation and platelet activation in the athlete: A comparison of marathon, triathlon and long distance cycling

    Directory of Open Access Journals (Sweden)

    Hanke AA

    2010-02-01

    Full Text Available Abstract Introduction Serious thrombembolic events occur in otherwise healthy marathon athletes during competition. We tested the hypothesis that during heavy endurance sports coagulation and platelets are activated depending on the type of endurance sport with respect to its running fraction. Materials and Methods 68 healthy athletes participating in marathon (MAR, running 42 km, n = 24, triathlon (TRI, swimming 2.5 km + cycling 90 km + running 21 km, n = 22, and long distance cycling (CYC, 151 km, n = 22 were included in the study. Blood samples were taken before and immediately after completion of competition to perform rotational thrombelastometry. We assessed coagulation time (CT, maximum clot firmness (MCF after intrinsically activation and fibrin polymerization (FIBTEM. Furthermore, platelet aggregation was tested after activation with ADP and thrombin activating peptide 6 (TRAP by using multiple platelet function analyzer. Results Complete data sets were obtained in 58 athletes (MAR: n = 20, TRI: n = 19, CYC: n = 19. CT significantly decreased in all groups (MAR -9.9%, TRI -8.3%, CYC -7.4% without differences between groups. In parallel, MCF (MAR +7.4%, TRI +6.1%, CYC +8.3% and fibrin polymerization (MAR +14.7%, TRI +6.1%, CYC +8.3% were significantly increased in all groups. However, platelets were only activated during MAR and TRI as indicated by increased AUC during TRAP-activation (MAR +15.8% and increased AUC during ADP-activation in MAR (+50.3% and TRI (+57.5%. Discussion While coagulation is activated during physical activity irrespective of type we observed significant platelet activation only during marathon and to a lesser extent during triathlon. We speculate that prolonged running may increase platelet activity, possibly, due to mechanical alteration. Thus, particularly prolonged running may increase the risk of thrombembolic incidents in running athletes.

  20. Psychological traits and platelet monoamine oxidase activity in eating disorder patients: their relationship and stability.

    Science.gov (United States)

    Podar, Iris; Jaanisk, Maiken; Allik, Jüri; Harro, Jaanus

    2007-01-30

    Self-reported behavior and attitudes towards eating [Eating Disorder Inventory-2; Garner DM (1991). Eating Disorder Inventory-2: Professional Manual. Odessa, Fl.: Psychological Assessment Resources; Estonian version Podar I, Hannus A, Allik J (1999). Personality and Affectivity Characteristics Associated With Eating Disorders: a Comparison of Eating Disordered, Weight-Preoccupied, and Normal Samples. J Pers Assess; 73(1), 133-147] and the activity of platelet monoamine oxidase (MAO) was studied in 11 patients with anorexia nervosa (AN), 43 patients with bulimia nervosa (BN) and a healthy control group (n=138). Nineteen patients filled in the EDI-2 questionnaire and donated blood samples three times with three month intervals in order to determine platelet MAO activity. Eating disordered (ED) patients scored higher on all EDI-2 subscales and had lower MAO activity compared to the control group. They also scored higher than the control group on the Neuroticism domain but lower on the Extraversion, Openness, and Conscientiousness domains of the NEO-PI-R questionnaire. The average stability of MAO on different occasions (r=.56) was slightly smaller than the stability of the EDI-2 scores (r=.70). The lack of correlations between personality dispositions and MAO activity indicates that they have independent influence on eating disorders. A possible relationship between neurochemical mechanisms and psychological symptoms of eating disordered behavior is discussed.

  1. Enhanced P-selectin expression on platelet-a marker of platelet activation, in young patients with angiographically proven coronary artery disease.

    Science.gov (United States)

    George, Reema; Bhatt, Anugya; Narayani, Jayakumari; Thulaseedharan, Jissa Vinoda; Sivadasanpillai, Harikrishnan; Tharakan, Jaganmohan A

    2016-08-01

    P-selectin (CD62p) exposure is an established marker for platelet activation. P-selectin exposure can trigger variety of thrombotic and inflammatory reactions. In patients with coronary artery disease (CAD), platelets are activated, and hence, there is increased P-selectin exposure. The role of P-selectin exposure in patients on treatment with statins and anti-platelets is conflicting. A case-control study was performed to determine P-selectin exposure in consecutively recruited 142 patients (age ≤ 55 years) with angiographically proven CAD on treatment and 92 asymptomatic controls. P-selectin exposure was determined by flow cytometry. Data on conventional risk factors were obtained along with estimation of levels of thrombotic [fibrinogen, lipoprotein (a), tissue plasminogen activator, plasminogen activator inhibitor-1, homocysteine and von Willebrand factor] and anti-thrombotic factors (antithrombin III). The P-selectin exposure was compared among patient groups who had different modes of presentation of CAD and categories of CAD disease severity. The patients were followed up for a period of 26 months. The results indicate that P-selectin exposure was significantly elevated in patients (mean ± SD 9.24 ± 11.81) compared to controls (mean ± SD 1.48 ± 2.85) with p P-selectin exposure showed significant negative correlation with antithrombin III levels. P-selectin exposure was higher in patients who presented with acute coronary syndromes than those who presented with effort angina. Cardiovascular event rate was 6 % on follow-up. The study establishes that thrombotic-inflammatory pathways enhancing P-selectin exposure unrelated to treatment might be activated in patients, while the event rate remained lowered, and hence, treatment strategies should be inclusive to control these factors.

  2. Fish-Free Diet in Patients with Phenylketonuria Is Not Associated with Early Atherosclerotic Changes and Enhanced Platelet Activation.

    Directory of Open Access Journals (Sweden)

    Patrik Htun

    Full Text Available Since patients with phenylketonuria (PKU have to follow a lifelong restriction of natural protein to lower phenylalanine-intake, they never eat fish. This diet may lead to a chronic deficit of omega-3 and omega-6 fatty acids with the risk of early atherosclerotic changes. The aim of the study was to analyse the fatty acid profile of PKU patients and to correlate the results with surrogate markers of early atherosclerotic changes [enhanced carotid intima media thickness (CIMT and ß-stiffness index] and platelet activation.In 43 PKU patients and in 58 healthy controls we prospectively examined the fatty acid profile, CIMT, ß-stiffness index and platelet activation (flow cytometric determination of markers of platelet activation. CIMT was measured bilaterally by ultrasound. CIMTmean was defined as the mean value of the sum of CIMTleft and CIMTright.Despite of lower HDL-cholesterol and higher triglyceride concentrations in the PKU group, there was no significant difference in the omega-6 or omega-3 fatty acid profile, CIMT, ß-stiffness index between both groups. Platelet activation was not enhanced in the PKU group.Fish-free diet does not induce early atherosclerotic changes or enhanced platelet activation in PKU patients.

  3. Influence of Cardiopulmonary Bypass on the Interaction of Recombinant Factor VIIa with Activated Platelets

    OpenAIRE

    Kjalke, Marianne; Runge, Marx; Rojkjaer, Rasmus; Steinbruchel, Daniel; Johansson, Pär I

    2009-01-01

    Recombinant factor VIIa (rFVIIa) interacts preferentially with coated platelets characterized by a high exposure of phosphatidyl serine (PS), FV, FVIII, FIX, and FX binding, and fibrinogen. Cardiopulmonary bypass (CPB) is known to impair platelet function. In this study, the influence of CPB on formation of coated platelets and the interaction of rFVIIa with the platelets were studied. Blood was either exposed to a closed CPB circuit or obtained from patients undergoing CPB-assisted cardiac s...

  4. New analogues of 13-hydroxyocatdecadienoic acid and 12-hydroxyeicosatetraenoic acid block human blood platelet aggregation and cyclooxygenase-1 activity

    Directory of Open Access Journals (Sweden)

    Hirz Taghreed

    2012-12-01

    Full Text Available Abstract Background Thromboxane A2 is derived from arachidonic acid through the action of cyclooxygenases and thromboxane synthase. It is mainly formed in blood platelets upon activation and plays an important role in aggregation. Aspirin is effective in reducing the incidence of complications following acute coronary syndrome and stroke. The anti-thrombotic effect of aspirin is obtained through the irreversible inhibition of cyclooxygenases. Analogues of 12-hydroxyeicosatetraenoic acid and 13-hydroxyocatdecadienoic acid were shown previously to modulate platelet activation and to block thromboxane receptors. Results and discussion We synthesized 10 compounds based on the structures of analogues of 12-hydroxyeicosatetraenoic acid and 13-hydroxyocatdecadienoic acid and evaluated their effect on platelet aggregation triggered by arachidonic acid. The structure activity relationship was evaluated. Five compounds showed a significant inhibition of platelet aggregation and highlighted the importance of the lipidic hydrophobic hydrocarbon chain and the phenol group. Their IC50 ranged from 7.5 ± 0.8 to 14.2 ± 5.7 μM (Mean ± S.E.M.. All five compounds decreased platelet aggregation and thromboxane synthesis in response to collagen whereas no modification of platelet aggregation in response to thromboxane receptor agonist, U46619, was observed. Using COS-7 cells overexpressing human cyclooxygenase-1, we showed that these compounds are specific inhibitors of cyclooxygenase-1 with IC50 ranging from 1.3 to 12 μM. Docking observation of human recombinant cyclooxygenase-1 supported a role of the phenol group in the fitting of cyclooxygenase-1, most likely related to hydrogen bonding with the Tyr 355 of cyclooxygenase-1. Conclusions In conclusion, the compounds we synthesized at first based on the structures of analogues of 12 lipoxygenase metabolites showed a role of the phenol group in the anti-platelet and anti-cyclooxygenase-1 activities

  5. Micro-structuring of polycarbonate-urethane surfaces in order to reduce platelet activation and adhesion.

    Science.gov (United States)

    Clauser, Johanna; Gester, Kathrin; Roggenkamp, Jan; Mager, Ilona; Maas, Judith; Jansen, Sebastian V; Steinseifer, Ulrich

    2014-01-01

    In the development of new hemocompatible biomaterials, surface modification appears to be a suitable method in order to reduce the thrombogenetic potential of such materials. In this study, polycarbonate-urethane (PCU) tubes with different surface microstructures to be used for aortic heart valve models were investigated with regard to the thrombogenicity. The surface structures were produced by using a centrifugal casting process for manufacturing PCU tubes with defined casting mold surfaces which are conferred to the PCU surface during the process. Tubes with different structures defined by altering groove widths were cut into films and investigated under dynamic flow conditions in contact with porcine blood. The analysis was carried out by laser scanning microscopy which allowed for counting various morphological types of platelets with regard to the grade of activation. The comparison between plain and shaped PCU samples showed that the surface topography led to a decline of the activation of the coagulation cascade and thus to the reduction of the fibrin synthesis. Comparing different types of structures revealed that smooth structures with a small groove width (d ~ 3 μm) showed less platelet activation as well as less adhesion in contrast to a distinct wave structure (d ~ 90 μm). These results prove surface modification of polymer biomaterials to be a suitable method for reducing thrombogenicity and hence give reason for further alterations and improvements.

  6. Hemolytic activity and platelet aggregation inhibitory effect of vipoxin's basic sPLA2 subunit

    Science.gov (United States)

    Goranova, Yana; Pantcheva, Ivayla; Atanasov, Vasil; Danchev, Dobri; Petrova, Svetla

    2013-01-01

    In the present study we evaluated the effect of secreted phospholipase A2 (sPLA2) (the toxic subunit of the heterodimeric neurotoxin vipoxin, isolated from the Bulgarian long-nosed viper Vipera ammodytes meridionalis) on hemolysis, erythrocyte morphology and platelet aggregation. Hemolytic activity of sPLA2 was examined in the presence of saturated (palmitic) and unsaturated (oleic) fatty acids and it was found that oleic acid increased the hemolytic activity of sPLA2 in a concentration-dependent manner, compared to the effect of palmitic acid and controls. The addition of heparin to red blood cells (RBC) suspension containing sPLA2 or mixture of sPLA2 and the corresponding fatty acid led to an inhibition of hemolytic activity. The effect of sPLA2 on RBC morphology resulted in formation of echinocytes (spherocyte subtype), suggesting that RBC could be the possible targets attacked by sPLA2. Vipoxin sPLA2 inhibited (in a dose-dependent manner) platelet aggregation when arachidonic acid and collagen were used as inducers, while in the case of ADP its inhibitory effect was inappreciable. PMID:24678250

  7. How do the full-generation poly(amido)amine (PAMAM) dendrimers activate blood platelets? Activation of circulating platelets and formation of "fibrinogen aggregates" in the presence of polycations.

    Science.gov (United States)

    Watala, Cezary; Karolczak, Kamil; Kassassir, Hassan; Talar, Marcin; Przygodzki, Tomasz; Maczynska, Katarzyna; Labieniec-Watala, Magdalena

    2016-04-30

    Direct use of poly(amido)amine (PAMAM) dendrimers as drugs may be limited, due to uncertain (cyto)toxicity. Peripheral blood components, which constitute the first line of a contact with administered pharmaceuticals, may become vastly affected by PAMAM dendrimers. The aim of this study was to explore how PAMAMs' polycationicity might affect blood platelet activation and reactivity, and thus trigger various haemostatic events. We monitored blood platelet reactivity in rats with experimental diabetes upon a long-term administration of the unmodified PAMAM dendrimers. In parallel, the effects on blood flow in a systemic circulation was recorded intravitally in mice administered with PAMAM G2, G3 or G4. Compounding was the in vitro approach to monitor the impact of PAMAM dendrimers on blood platelet activation and reactivity and on selected haemostatic and protein conformation parameters. We demonstrated the activating effects of polycations on blood platelets. Some diversity of the revealed outcomes considerably depended on the used approach and the particular technique employed to monitor blood platelet function. We discovered undesirable impact of plain PAMAM dendrimers on primary haemostasis and their prothrombotic influence. We emphasize the need of a more profound verifying of all the promising findings collected for PAMAMs with the use of well-designed in vivo preclinical studies.

  8. Potential Participation of calpain in platelet activation studied by use of a cell penetrating calpain inhibitor (Calpeptin)

    Energy Technology Data Exchange (ETDEWEB)

    Tsujinaka, Toshimasa; Ariyoshi, Hideo; Uemura, Yoshio; Sakon, Masato; Kambayashi, Junichi; Mori, Takesada (Osaka Univ. Medical School, Fukushima (Japan))

    1990-01-01

    Employing a cell penetrating calpain inhibitor (calpeptin), the role of calpain in platelet activation was examined. In washed platelets (WPs) both thrombin and collagen-induced platelet aggregation were dose-dependently inhibited by calpeptin. The addition of plasma to WPs interfered with the action of calpeptin, however more than 3 min preincubation of calpeptin with WPs completely abolished the influence of plasma. In thrombin-activated WPs with calcium, the increase of intracellular calcium concentration, (Ca{sup 2+})i, and the production of inositol triphosphate (IP{sub 3}) were dose-dependently inhibited by calpeptin. The generation of thromboxane B{sub 2} (TxB{sub 2}) was inhibited by calpeptin in collagen and thrombin-activated WPs. In ({sub 3}H)-arachidonic acid (AA)-labelled platelets, calpeptin increased the amount of ({sup 3}H)-AA liberated by inhibiting ({sup 3}H)-AA degradation after collagen or thrombin stimulation. When ({sup 14}C)-AA degradation by the platelet suspension was observed, calpeptin inhibited TxB{sub 2} and hydroxyheptadecatrienoic acid (HHT) generation but increased prostaglandin (PG) E{sub 1}, E{sub 2}, 12-hydroxyeicosatetraenoic acid (12HETE) and AA. Based on these findings, calpain may be involved in the activation phospholipase C and thromboxane synthetase.

  9. Discovering anti-platelet drug combinations with an integrated model of activator-inhibitor relationships, activator-activator synergies and inhibitor-inhibitor synergies.

    Directory of Open Access Journals (Sweden)

    Federica Lombardi

    2015-04-01

    Full Text Available Identifying effective therapeutic drug combinations that modulate complex signaling pathways in platelets is central to the advancement of effective anti-thrombotic therapies. However, there is no systems model of the platelet that predicts responses to different inhibitor combinations. We developed an approach which goes beyond current inhibitor-inhibitor combination screening to efficiently consider other signaling aspects that may give insights into the behaviour of the platelet as a system. We investigated combinations of platelet inhibitors and activators. We evaluated three distinct strands of information, namely: activator-inhibitor combination screens (testing a panel of inhibitors against a panel of activators; inhibitor-inhibitor synergy screens; and activator-activator synergy screens. We demonstrated how these analyses may be efficiently performed, both experimentally and computationally, to identify particular combinations of most interest. Robust tests of activator-activator synergy and of inhibitor-inhibitor synergy required combinations to show significant excesses over the double doses of each component. Modeling identified multiple effects of an inhibitor of the P2Y12 ADP receptor, and complementarity between inhibitor-inhibitor synergy effects and activator-inhibitor combination effects. This approach accelerates the mapping of combination effects of compounds to develop combinations that may be therapeutically beneficial. We integrated the three information sources into a unified model that predicted the benefits of a triple drug combination targeting ADP, thromboxane and thrombin signaling.

  10. A novel antithrombotic effect of sulforaphane via activation of platelet adenylate cyclase: ex vivo and in vivo studies.

    Science.gov (United States)

    Jayakumar, Thanasekaran; Chen, Wei-Fan; Lu, Wan-Jung; Chou, Duen-Suey; Hsiao, George; Hsu, Chung-Yi; Sheu, Joen-Rong; Hsieh, Cheng-Ying

    2013-06-01

    Sulforaphane is a naturally occurring isothiocyanate, which can be found in cruciferous vegetables such as broccoli and cabbage. Sulforaphane was found to have very potent inhibitory effects on tumor growth through regulation of diverse mechanisms. However, no data are available concerning the effects of sulforaphane on platelet activation and its relative issues. Activation of platelets caused by arterial thrombosis is relevant to a variety of cardiovascular diseases. Hence, the aim of this study was to examine the in vivo antithrombotic effects of sulforaphane and its possible mechanisms in platelet activation. Sulforaphane (0.125 and 0.25 mg/kg) was effective in reducing the mortality of ADP-induced acute pulmonary thromboembolism in mice. Other in vivo studies also revealed that sulforaphane (0.25 mg/kg) significantly prolonged platelet plug formation in mice. In addition, sulforaphane (15-75 μM) exhibited more-potent activity of inhibiting platelet aggregation stimulated by collagen. Sulforaphane inhibited platelet activation accompanied by inhibiting relative Ca(2+) mobilization; phosphorylation of phospholipase C (PLC)γ2, protein kinase C (PKC), mitogen-activated protein kinases (MAPKs) and Akt; and hydroxyl radical (OH(●)) formation. Sulforaphane markedly increased cyclic (c)AMP, but not cyclic (c)GMP levels, and stimulated vasodilator-stimulated phosphoprotein (VASP) phosphorylation. SQ22536, an inhibitor of adenylate cyclase, but not ODQ (1H-[1,2,4]Oxadiazolo[4,3-a]quinoxal in-1-one), an inhibitor of guanylate cyclase, obviously reversed the sulforaphane-mediated effects on platelet aggregation; PKC activation, p38 MAPK, Akt and VASP phosphorylation; and OH(●) formation. Furthermore, a PI3-kinase inhibitor (LY294002) and a p38 MAPK inhibitor (SB203580) both significantly diminished PKC activation and p38 MAPK and Akt phosphorylation; in contrast, a PKC inhibitor (RO318220) did not diminish p38 MAPK or Akt phosphorylation stimulated by collagen. This

  11. Oligomeric state regulated trafficking of human platelet-activating factor acetylhydrolase type-II.

    Science.gov (United States)

    Monillas, Elizabeth S; Caplan, Jeffrey L; Thévenin, Anastasia F; Bahnson, Brian J

    2015-05-01

    The intracellular enzyme platelet-activating factor acetylhydrolase type-II (PAFAH-II) hydrolyzes platelet-activating factor and oxidatively fragmented phospholipids. PAFAH-II in its resting state is mainly cytoplasmic, and it responds to oxidative stress by becoming increasingly bound to endoplasmic reticulum and Golgi membranes. Numerous studies have indicated that this enzyme is essential for protecting cells from oxidative stress induced apoptosis. However, the regulatory mechanism of the oxidative stress response by PAFAH-II has not been fully resolved. Here, changes to the oligomeric state of human PAFAH-II were investigated as a potential regulatory mechanism toward enzyme trafficking. Native PAGE analysis in vitro and photon counting histogram within live cells showed that PAFAH-II is both monomeric and dimeric. A Gly-2-Ala site-directed mutation of PAFAH-II demonstrated that the N-terminal myristoyl group is required for homodimerization. Additionally, the distribution of oligomeric PAFAH-II is distinct within the cell; homodimers of PAFAH-II were localized to the cytoplasm while monomers were associated to the membranes of the endoplasmic reticulum and Golgi. We propose that the oligomeric state of PAFAH-II drives functional protein trafficking. PAFAH-II localization to the membrane is critical for substrate acquisition and effective oxidative stress protection. It is hypothesized that the balance between monomer and dimer serves as a regulatory mechanism of a PAFAH-II oxidative stress response.

  12. Effects of simvastatin on lipid levels and platelet activation in elderly patients with hypercholesterolemia

    Institute of Scientific and Technical Information of China (English)

    Zhe Chen; Yuanping Hou; Miaobin Liu

    2007-01-01

    Background and Objective To investigate the effects of simvastatin on lipid lowering therapy and platelet activation in elderly patients with hypercholesterolemia. Methods Fasting serum lipids, CD63, CD41a, serum glucose, hepatic and renal function, routine urine analysis (UA) were measured in 50 healthy subjects, and in 50 elderly patients with hypercholesterolemia before and after 4 weeks treatment with simvastatin (20mg daily for 4 weeks). Results 1. After simvastatin treatment for 4 weeks, the fasting serum level of lipids in elderly patients with hypercholesterolemia was significantly lower than before treatment (P<0.01). 2. CD63 and CD41a were decreased after treatment compared with before, respectively (1.36 0.34) vs (4.26 1.06), (P<0.01) and (123.54 19.73) vs (253.78 16.75), (P<0.01).3. Changes in serum lipid level tended to be positively correlated with the declines in CD63 and CD41a, but there was no statistical significance (P>0.05). Conclusions The results suggested that lipid lowering therapy with simvastatin inhibit platelet activity.

  13. Therapy for acute pancreatitis with platelet-activating factor receptor antagonists

    Institute of Scientific and Technical Information of China (English)

    Chong Chen; Shi-Hai Xia; Hong Chen; Xiao-Hong Li

    2008-01-01

    Acute pancreatitis (AP) causes release of plateletactivating factor (PAF),which induces systemic effects that contribute to circulatory disturbances and multiple organ failure.PAF is a cell surface secretion of bioactive lipid,which could produce physiological and pathological effects by binding to its cell surface receptor called platelet-activating factor receptor (PAF-R).Studies showed that PAF participates in the occurrence and development of AP and administration of platelet-activating factor receptor antagonists (PAF-RAs) could significantly reduce local and systemic events after AP.PAF has also been implicated as a key mediator in the progression of severe AP,which can lead to complications and unacceptably high mortality rates.Several classes of PAF-RA show PAFRAs significant local and systemic effects on reducing inflammatory changes.As a preventive treatment,PAF-RA could block a series of PAF-mediatedinflammatory injury and thus improve the prognosis of AR This review introduces the important role of PAF-RA in the treatment of AP.

  14. High levels of LDL-C combined with low levels of HDL-C further increase platelet activation in hypercholesterolemic patients.

    Science.gov (United States)

    Chan, L W; Luo, X P; Ni, H C; Shi, H M; Liu, L; Wen, Z C; Gu, X Y; Qiao, J; Li, J

    2015-02-01

    High levels of low-density lipoprotein cholesterol (LDL-C) enhance platelet activation, whereas high levels of high-density lipoprotein cholesterol (HDL-C) exert a cardioprotective effect. However, the effects on platelet activation of high levels of LDL-C combined with low levels of HDL-C (HLC) have not yet been reported. We aimed to evaluate the platelet activation marker of HLC patients and investigate the antiplatelet effect of atorvastatin on this population. Forty-eight patients with high levels of LDL-C were enrolled. Among these, 23 had HLC and the other 25 had high levels of LDL-C combined with normal levels of HDL-C (HNC). A total of 35 normocholesterolemic (NOMC) volunteers were included as controls. Whole blood flow cytometry and platelet aggregation measurements were performed on all participants to detect the following platelet activation markers: CD62p (P-selectin), PAC-1 (GPIIb/IIIa), and maximal platelet aggregation (MPAG). A daily dose of 20 mg atorvastatin was administered to patients with high levels of LDL-C, and the above assessments were obtained at baseline and after 1 and 2 months of treatment. The expression of platelets CD62p and PAC-1 was increased in HNC patients compared to NOMC volunteers (PHDL-C further increased platelet activation in patients with high levels of LDL-C. Platelet activation remained higher among HLC patients regardless of atorvastatin treatment.

  15. Cystamine immobilization on TiO 2 film surfaces and the influence on inhibition of collagen-induced platelet activation

    Science.gov (United States)

    Zhou, Yujuan; Weng, Yajun; Zhang, Liping; Jing, Fengjuan; Huang, Nan; Chen, Junying

    2011-12-01

    Poor haemocompatibility is a main issue of artificial cardiovascular materials in clinical application. Nitric oxide (NO), produced by vascular endothelial cells, is a well known inhibitor of platelet adhesion and activation. Thus, NO-releasing biomaterials are beneficial for improving haemocompatibility of blood-contacting biomedical devices. In this paper, a novel method was developed for enhancement of haemocompatibility by exploiting endogenous NO donors. TiO 2 films were firstly synthesized on Si (1 0 0) wafers via unbalanced magnetron sputtering technology, and then polydopamine was grafted on TiO 2 films and used as a linker for further immobilization of cystamine. The obtained surfaces were characterized by scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) analysis. NO generation is evaluated by saville-griess reagents, and it shows that cystamine immobilized samples are able to catalytically generate NO by decomposing endogenous S-nitrosothiols (RSNO). In vitro platelet adhesion results reveal that cystamine modified surfaces can inhibit collagen-induced platelet activation. ELISA analysis reveals that cGMP in platelets obviously increases on cystamine immobilized surface, which suggests the reducing of platelet activation is through NO/cGMP signal channel. It can be concluded that cystamine immobilized surface shows better blood compatibility by catalyzing NO release from the endogenous NO donor. It may be a promising method for improvement of haemocompatibility of blood-contacting implants.

  16. Intranasal exposure to amorphous nanosilica particles could activate intrinsic coagulation cascade and platelets in mice

    Science.gov (United States)

    2013-01-01

    Background Nanomaterials with particle sizes coagulation system. Methods We used nanosilica particles with diameters of 30, 70, or 100 nm (nSP30, nSP70, or nSP100 respectively), and conventional microscale silica particles with diameters of 300 or 1000 nm (mSP300 or mSP1000, respectively). BALB/c mice were intranasally exposed to nSP30, nSP70, nSP100, mSP300, or mSP1000 at concentrations of 500 μg/mouse for 7 days. After 24 hours of last administration, we performed the in vivo transmission electron microscopy analysis, hematological examination and coagulation tests. Results In vivo transmission electron microscopy analysis showed that nanosilica particles with a diameter coagulation tests showed that platelet counts decreased and that the activated partial thromboplastin time was prolonged in nSP30 or nSP70-treated groups of mice, indicating that nanosilica particles might have activated a coagulation cascade. In addition, in in vitro activation tests of human plasma, nanosilica particles had greater potential than did conventional microscale silica particles to activate coagulation factor XII. In nanosilica-particle-treated groups, the levels of soluble CD40 ligand, and von Willebrand factor which are involved in stimulating platelets tended to slightly increase with decreasing particle size. Conclusions These results suggest that intranasally administered nanosilica particles with diameters of 30 and 70 nm could induce abnormal activation of the coagulation system through the activation of an intrinsic coagulation cascade. This study provides information to advance the development of safe and effective nanosilica particles. PMID:23958113

  17. Platelet-Derived Short-Chain Polyphosphates Enhance the Inactivation of Tissue Factor Pathway Inhibitor by Activated Coagulation Factor XI

    Science.gov (United States)

    Puy, Cristina; Tucker, Erik I.; Ivanov, Ivan S.; Gailani, David; Smith, Stephanie A.; Morrissey, James H.; Gruber, András; McCarty, Owen J. T.

    2016-01-01

    Introduction Factor (F) XI supports both normal human hemostasis and pathological thrombosis. Activated FXI (FXIa) promotes thrombin generation by enzymatic activation of FXI, FIX, FX, and FV, and inactivation of alpha tissue factor pathway inhibitor (TFPIα), in vitro. Some of these reactions are now known to be enhanced by short-chain polyphosphates (SCP) derived from activated platelets. These SCPs act as a cofactor for the activation of FXI and FV by thrombin and FXIa, respectively. Since SCPs have been shown to inhibit the anticoagulant function of TFPIα, we herein investigated whether SCPs could serve as cofactors for the proteolytic inactivation of TFPIα by FXIa, further promoting the efficiency of the extrinsic pathway of coagulation to generate thrombin. Methods and Results Purified soluble SCP was prepared by size-fractionation of sodium polyphosphate. TFPIα proteolysis was analyzed by western blot. TFPIα activity was measured as inhibition of FX activation and activity in coagulation and chromogenic assays. SCPs significantly accelerated the rate of inactivation of TFPIα by FXIa in both purified systems and in recalcified plasma. Moreover, platelet-derived SCP accelerated the rate of inactivation of platelet-derived TFPIα by FXIa. TFPIα activity was not affected by SCP in recalcified FXI-depleted plasma. Conclusions Our data suggest that SCP is a cofactor for TFPIα inactivation by FXIa, thus, expanding the range of hemostatic FXIa substrates that may be affected by the cofactor functions of platelet-derived SCP. PMID:27764259

  18. In vivo and protease-activated receptor-1-mediated platelet activation but not response to antiplatelet therapy predict two-year outcomes after peripheral angioplasty with stent implantation.

    Science.gov (United States)

    Gremmel, T; Steiner, S; Seidinger, D; Koppensteiner, R; Panzer, S; Kopp, C W

    2014-03-01

    Data linking the response to antiplatelet therapy with clinical outcomes after angioplasty and stenting for lower extremity artery disease (LEAD) are scarce. Moreover, associations of in vivo and thrombin-inducible platelet activation with the occurrence of adverse events have not been investigated in these patients, so far. We therefore assessed clinical outcomes and on-treatment platelet reactivity by four test systems in 108 patients receiving dual antiplatelet therapy after infrainguinal angioplasty and stenting for LEAD. Further, in vivo and thrombin receptor-activating peptide (TRAP)-6-inducible glycoprotein (GP) IIb/IIIa activation and P-selectin expression were measured as sensitive parameters of platelet activation. The primary endpoint was defined as the composite of atherothrombotic events and target vessel restenosis or reocclusion. Residual platelet reactivity to adenosine diphosphate and arachidonic acid was similar between patients without and with adverse outcomes within two-year follow-up (all p>0.05). Further, the occurrence of clinical endpoints did not differ significantly between patients without and with high on-treatment residual platelet reactivity by all test systems (all p>0.05). In contrast, in vivo and TRAP-6-inducible platelet activation were significantly more pronounced in patients with subsequent adverse events (all pangioplasty and stenting for LEAD.

  19. Activated platelets in carotid artery thrombosis in mice can be selectively targeted with a radiolabeled single-chain antibody.

    Directory of Open Access Journals (Sweden)

    Timo Heidt

    Full Text Available BACKGROUND: Activated platelets can be found on the surface of inflamed, rupture-prone and ruptured plaques as well as in intravascular thrombosis. They are key players in thrombosis and atherosclerosis. In this study we describe the construction of a radiolabeled single-chain antibody targeting the LIBS-epitope of activated platelets to selectively depict platelet activation and wall-adherent non-occlusive thrombosis in a mouse model with nuclear imaging using in vitro and ex vivo autoradiography as well as small animal SPECT-CT for in vivo analysis. METHODOLOGY/PRINCIPAL FINDINGS: LIBS as well as an unspecific control single-chain antibody were labeled with (111Indium ((111In via bifunctional DTPA ( = (111In-LIBS/(111In-control. Autoradiography after incubation with (111In-LIBS on activated platelets in vitro (mean 3866 ± 28 DLU/mm(2, 4010 ± 630 DLU/mm(2 and 4520 ± 293 DLU/mm(2 produced a significantly higher ligand uptake compared to (111In-control (2101 ± 76 DLU/mm(2, 1181 ± 96 DLU/mm(2 and 1866 ± 246 DLU/mm(2 indicating a specific binding to activated platelets; P<0.05. Applying these findings to an ex vivo mouse model of carotid artery thrombosis revealed a significant increase in ligand uptake after injection of (111In-LIBS in the presence of small thrombi compared to the non-injured side, as confirmed by histology (49630 ± 10650 DLU/mm(2 vs. 17390 ± 7470 DLU/mm(2; P<0.05. These findings could also be reproduced in vivo. SPECT-CT analysis of the injured carotid artery with (111In-LIBS resulted in a significant increase of the target-to-background ratio compared to (111In-control (1.99 ± 0.36 vs. 1.1 ± 0.24; P < 0.01. CONCLUSIONS/SIGNIFICANCE: Nuclear imaging with (111In-LIBS allows the detection of platelet activation in vitro and ex vivo with high sensitivity. Using SPECT-CT, wall-adherent activated platelets in carotid arteries could be depicted in vivo. These results encourage further studies elucidating the role of

  20. Lymphocyte-platelet crosstalk in Graves' disease.

    Science.gov (United States)

    Kuznik, Boris I; Vitkovsky, Yuri A; Gvozdeva, Olga V; Solpov, Alexey V; Magen, Eli

    2014-03-01

    Platelets can modulate lymphocytes' role in the pathophysiology of thyroid autoimmune diseases. The present study was performed to clarify the status of platelet-lymphocyte subpopulations aggregation in circulating blood in patients with Graves' disease (GD). One hundred and fifty patients with GD (GD group) and 45 hyperthyroid patients with toxic multinodular goiter (TMG group) were recruited in the study. Control group consisted 150 healthy subjects. Immunophenotyping of lymphocytes was performed by flow cytometry. Detection of lymphocyte-platelet aggregates (LPAs) was done using light microscope after Ficoll-gradient centrifugation. The group of GD patients exhibited reduced CD8 lymphocyte and higher CD19 cell counts compared with TMG group and healthy controls. A greater number of activated CD3, HLA-DR+ lymphocytes were observed in GD than in TMG group and control group. GD group was characterized by lower blood platelet count (232 ± 89 × 10 cells/µL) than TMG group (251 ± 97 × 10 cells/µL; P < 0.05) and control group (262 ± 95 × 10 cells/µL; P < 0.05). In GD group, more platelet-bound lymphocytes (332 ± 91 /µL) were found than that in TMG group (116 ± 67/µL, P < 0.005) and control group (104 ± 58 /µL; P < 0.001). GD is associated with higher levels of activated lymphocytes and lymphocyte-platelet aggregates.

  1. Inflammation, oxidative stress and platelet activation in aspirin-treated critical limb ischaemia: beneficial effects of iloprost.

    Science.gov (United States)

    Lessiani, Gianfranco; Vazzana, Natale; Cuccurullo, Chiara; Di Michele, Dario; Laurora, Giuseppe; Sgrò, Giuseppe; Di Ruscio, Paolo; Simeone, Emilio; Di Iorio, Pierangelo; Lattanzio, Stefano; Liani, Rossella; Ferrante, Elisabetta; Davì, Giovanni

    2011-02-01

    Platelets critically contribute to atherothrombosis and worsening ischaemia in patients with peripheral arterial disease (PAD), eventually leading to critical limb ischaemia (CLI). Furthermore, persistent platelet activation despite antiplatelet therapy has been reported in this setting. The prostacyclin analogue iloprost is currently recommended in CLI patients for its effects in relieving symptoms by promoting local perfusion. In this study, we investigated the effects of iloprost infusion on urinary 11-dehydro-TXB₂ and 8-iso-PGF(₂α) excretion rate, as in vivo indexes of thromboxane-dependent platelet activation and lipid peroxidation, respectively, and on platelet-derived proinflammatory sCD40L and nitric oxide bioavailability in 44 patients with CLI while on chronic treatment with low-dose aspirin. Daily iloprost infusion for one-week significantly decreased urinary 11-dehydro-TXB₂ [499 (277-807) vs. 380 (189-560) pg/mg creatinine, p iloprost treatment (Rho = 0.695, p iloprost is able to significantly reduce residual thromboxane biosynthesis, oxidative stress, endothelial dysfunction and platelet-derived inflammation in low-dose aspirin treated patients with CLI.

  2. Dengue fever activates the L-arginine-nitric oxide pathway: an explanation for reduced aggregation of human platelets.

    Science.gov (United States)

    Mendes-Ribeiro, Antonio C; Moss, Monique B; Siqueira, Mariana As; Moraes, Thalyta L; Ellory, J Clive; Mann, Giovanni E; Brunini, Tatiana Mc

    2008-10-01

    In patients with Dengue fever, a viral inflammatory syndrome, haemorrhage is a significant pathological feature, yet the underlying mechanisms remain unclear. Nitric oxide (NO) is an important regulator of platelet function, inhibiting aggregation, recruitment and adhesion to the vascular endothelium. We have investigated whether changes in the activity of the L-arginine-NO pathway in human platelets may account for increased bleeding in patients with Dengue fever. A total of 16 patients with Dengue fever and 18 age-matched healthy volunteers participated in the study. Collagen induced platelet aggregation in a dose-dependent manner in both Dengue patients and controls, but the degree of platelet aggregation was significantly reduced in the patient group. Elevated rates of L-arginine transport in Dengue fever patients were associated with enhanced NO synthase activity and elevated plasma fibrinogen levels. The present study provides the first evidence that Dengue fever is associated with increased L-arginine transport and NO generation and reduced platelet aggregation.

  3. Pro-thrombotic effect of exercise in a polluted environment: a P-selectin- and CD63-related platelet activation effect.

    Science.gov (United States)

    Wauters, Aurélien; Esmaeilzadeh, Fatemeh; Bladt, Sandrine; Beukinga, Ingrid; Wijns, Walter; van de Borne, Philippe; Pradier, Olivier; Argacha, Jean-François

    2015-01-01

    Exposure to diesel exhaust is an important cardiovascular risk factor and may promote atherothrombotic events. Some data suggest that polluted air exposure could affect haemostasis through platelet activation. The aim of the study was to investigate the effects of acute exposure to diesel exhaust on platelet activation and platelet function. We tested the hypothesis in a randomised, crossover study in 25 healthy men exposed to ambient and polluted air; 11 of the subjects also performed exercise during exposure sessions. Platelet activation was evaluated by surface expression of CD62P (P-selectin) and CD63 (dense granule glycoprotein) using flow cytometry of labelled platelets. Platelet function was measured using the PFA-100 platelet function analyser and by Multiplate whole blood impedance platelet aggregometry. Acute diesel exhaust exposure had no effect on platelet activation at rest, but exercise in polluted air increased the collagen-induced expression of CD62P and CD63 (both p< 0.05). The increase in the expression of CD62P and CD63 was related to the total amount of PM2.5 inhaled during the exercise sessions (r=+0.58 and +0.60, respectively, both p< 0.05). Platelet aggregation was not impaired after polluted air exposure at rest or during exercise. In conclusion, in healthy subjects, diesel exhaust exposure induces platelet activation as illustrated by a dose-response increase in the release of CD62P and CD63. This platelet priming effect could be a contributor to the triggering of atherothrombotic events related to air pollution exposure.

  4. Relationship between Platelet PPARs, cAMP Levels, and P-Selectin Expression: Antiplatelet Activity of Natural Products

    Science.gov (United States)

    Fuentes, Eduardo; Palomo, Iván

    2013-01-01

    Platelets are no longer considered simply as cells participating in thrombosis. In atherosclerosis, platelets are regulators of multiple processes, with the recruitment of inflammatory cells towards the lesion sites, inflammatory mediators release, and regulation of endothelial function. The antiplatelet therapy has been used for a long time in an effort to prevent and treat cardiovascular diseases. However, limited efficacy in some patients, drug resistance, and side effects are limitations of current antiplatelet therapy. In this context, a large number of natural products (polyphenols, terpenoids, alkaloids, and fatty acids) have been reported with antiplatelet activity. In this sense, the present paper describes mechanisms of antiplatelet action of natural products on platelet P-selectin expression through cAMP levels and its role as peroxisome proliferator-activated receptors agonists. PMID:24324520

  5. Relationship between Platelet PPARs, cAMP Levels, and P-Selectin Expression: Antiplatelet Activity of Natural Products

    Directory of Open Access Journals (Sweden)

    Eduardo Fuentes

    2013-01-01

    Full Text Available Platelets are no longer considered simply as cells participating in thrombosis. In atherosclerosis, platelets are regulators of multiple processes, with the recruitment of inflammatory cells towards the lesion sites, inflammatory mediators release, and regulation of endothelial function. The antiplatelet therapy has been used for a long time in an effort to prevent and treat cardiovascular diseases. However, limited efficacy in some patients, drug resistance, and side effects are limitations of current antiplatelet therapy. In this context, a large number of natural products (polyphenols, terpenoids, alkaloids, and fatty acids have been reported with antiplatelet activity. In this sense, the present paper describes mechanisms of antiplatelet action of natural products on platelet P-selectin expression through cAMP levels and its role as peroxisome proliferator-activated receptors agonists.

  6. [Comparative evaluation of the efficiency of the effect of very high frequency electromagnetic waves on platelet functional activity].

    Science.gov (United States)

    Kirichuk, V F; Maĭborodin, A V; Volin, M V; Krenitskiĭ, A P; Tupikin, V D

    2001-01-01

    A comparative analysis was made of the effect of two kinds of EMI MMD-radiation: EMI MMD-waves, generated by a vehicle "Jav-1 M" (42.2 and 53.5 HHz), and EMI MMD-waves exerting influence with frequencies of molecular spectrum of radiation and nitric oxide absorption (150.176-150.644 HHz), obtained with a specially created generator, with respect to their influence on the functional ability of platelets of unstable angina pectoris patients. It was shown that in vitro EMI MMD-fluctuations with frequencies of molecular spectrum of radiation and nitric oxide absorption exert a stronger inhibiting influence on the functional activity of platelets of unstable angina pectoris patients. Features of the action of various kinds of EMI MMD-effect on the activative-high-speed characteristics of platelet aggregation are shown.

  7. Label-free Detection of Protein Released during Platelet Activation by CNT-Enhanced Love Mode SAW Sensors.

    Science.gov (United States)

    Wu, Huiyan; Zu, Hongfei; Wang, Qing-Ming; Zhao, Gangyi; Wang, Jamesu H-C

    2014-09-01

    Platelet-rich plasma (PRP) has been applied in a series of clinical treatments. PRP contains high-concentrated platelets, which, when activated, could secret a variety of growth factors and cytokines, to promote and/or enhance healing of injured tissues. Non-activated platelets suspension could be prepared by an isolation method of centrifugation and washing currently. However, it is not clear whether platelets, if any, are already activated during this process and there is no simple method to monitor their activation accordingly. Shear-Horizontal Surface Acoustic Wave sensors (SH-SAW, Love Mode) are promising in fundamental biology as well as biomedical engineering, detecting cell behaviors in liquid in a non-invasive, simple and quantitative manner. In this study, Love mode sensors are adopted for the label-free detection of protein secreted by platelets. Carbon nanotube (CNT) is reported as an advisable platform of both non-specific protein adsorption and specific protein binding. For further improvement of Love mode sensor performance, novel CNT -coated parylene-C film is prepared on its surface as both the acoustic-wave-guiding layer and bio-interface layer. The S21 loss curves of Love mode sensors were recorded and the corresponding resonance frequencies were extracted. The results showed that the CNT-enhanced sensor possessed an increased resonance frequency shift when compared to normal sensor with single parylene-C film under identical collagen concentrations. Then, the modified sensor is used for label-free detection of protein released by various concentrations of platelets. The results revealed high sensitivity and consistency, indicating the potential of CNT-enhanced Love mode sensors in cell-based applications.

  8. Valsartan Decreases Platelet Activity and Arterial Thrombotic Events in Elderly Patients with Hypertension

    Institute of Scientific and Technical Information of China (English)

    Fang Wu; Hong-Yan Wang; Fan Cai; Ling-Jie Wang; Feng-Ru Zhang; Xiao-Nan Chen; Qian Yang

    2015-01-01

    Background:Angiotensin type 1 receptor (AT1R) antagonists are extensively used for blood pressure control in elderly patients with hypertension.This study aimed to investigate the inhibitory effects of AT1R antagonist valsartan on platelet aggregation and the occurrence of cardio-cerebral thrombotic events in elderly patients with hypertension.Methods:Two-hundred and ten patients with hypertension and aged > 60 years were randomized to valsartan (n =140) or amlodipine (n =70) on admission.The primary endpoint was platelet aggregation rate (PAR) induced by arachidonic acid at discharge,and the secondary endpoint was the rate of thrombotic events including brain infarction and myocardial infarction during follow-up.Human aortic endothelial cells (HAECs) were stimulated by angiotensin Ⅱ (Ang Ⅱ,100 nmol/L) with or without pretreatment of valsartan (100 nmol/L),and relative expression of cyclooxygenase-2 (COX-2) and thromboxane B2 (TXB2) and both p38 mitogen-activated protein kinase (p38MAPK) and nuclear factor-kB (NF-kB) activities were assessed.Statistical analyses were performed by GraphPad Prism 5.0 software (GraphPad Software,Inc.,California,USA).Results:PAR was lower after treatment with valsartan (1 1.49 ± 0.69% vs.18.71 ± 2.47%,P < 0.001),associated with more reduced plasmalevels of COX-2 (76.94 ± 7.07 U/L vs.116.4 ± 15.89 U/L,P < 0.001) and TXB2 (1667 ± 56.50 pg/ml vs.2207 ± 180.20 pg/ml) (all P < 0.001).Plasma COX-2 and TXB2 levels correlated significantly with PAR in overall patients (r =0.109,P < 0.001).During follow-up (median,18 months),there was a significantly lower thrombotic event rate in patients treated with valsartan (14.3% vs.32.8%,P =0.002).Relative expression of COX-2 and secretion of TXB2 with concordant phosphorylation ofp38MAPK and NF-kB were increased in HAECs when stimulated by Ang Ⅱ (100 nmol/L) but were significantly decreased by valsartan pretreatment (100 nmol/L).Conclusions:AT1R antagonist valsartan

  9. Clinical application of radiolabelled platelets

    Energy Technology Data Exchange (ETDEWEB)

    Kessler, C. (Medical University Luebeck (Federal Republic of Germany). Department of Neurology); Hardeman, M.R. (Amsterdam Univ. (Netherlands). Academisch Ziekenhuis); Henningsen, H. (Heidelberg Univ. (Germany, F.R.). Neurologische Klinik); Petrovici, J.-N. (Cologne-Merheim Hospital (Federal Republic of Germany). Department of Neurology) (eds.)

    1990-01-01

    The increasing number of therapeutic modalities available for the management of patients with thromboembolic complications, such as fibrinolytic treatment or vascular surgery, require the development of new imaging techniques to provide more information on the xtent, age and activity of the thromboembolic material causing clinical symptoms. Since the introduction of radiolabelling of platelets with indium-111, platelet scintigraphy (PSC) has been used as a tool in the diagnosis of various thromboembolic diseases. During the International Symposium on Radiolabelled Platelets scientists from a variety of medical backgrounds presented their results on the clinical applictions of radiolabelled platelets. The papers presented there have been updated to take account of the latest results before publication in this volume. The papers are grouped into six sections on platelet labelling techniques, radiolabelled platelets in cardiology, monitoring of antiplatelet therapy, platelet scintigraphy in stroke patients, platelet scintigraphy in angiology, and platelet scintigraphy in hematology and other clinical applications, including renal transplant rejection. refs.; figs.; tabs.

  10. TRA-418, a novel compound having both thromboxane A(2) receptor antagonistic and prostaglandin I(2) receptor agonistic activities: its antiplatelet effects in human and animal platelets.

    Science.gov (United States)

    Yamada, N; Miyamoto, M; Isogaya, M; Suzuki, M; Ikezawa, S; Ohno, M; Otake, A; Umemura, K

    2003-08-01

    TRA-418 is a novel compound that has been found in our screening for compounds having both thromboxane A2 (TP) receptor antagonistic and prostaglandin I2 (IP) receptor agonistic activities. In the binding assays, TRA-418 showed a 10-fold higher affinity to TP-receptors than IP-receptors. TRA-418 inhibited platelet aggregation induced by the TP-receptor agonist, U-46619 and by arachidonic acid at concentrations lower than those required for inhibition of ADP-induced aggregations. Furthermore, TRA-418 inhibited not only platelet aggregation induced by ADP alone, but also that induced by ADP in the presence of the TP-receptor antagonist, SQ-29548. When the IC50 values of TRA-418 for platelet aggregation were estimated in platelet preparations from monkeys, dogs, cats, and rats using ADP and arachidonic acid as the platelet stimulating agents, it was found that the values estimated in monkey platelets were quite similar to those estimated in human platelets. In ex vivo platelet aggregation in monkeys, TRA-418 exhibited significant inhibitory effects on arachidonic acid-induced aggregation in platelet preparations from monkeys treated at 3 micro g kg min-1 or higher doses, where neither a significant decrease in blood pressure nor a significant increase in heart rate was observed. These results are consistent with the fact that TRA-418 has a relatively potent TP-receptor antagonistic activity together with a relatively weak IP-receptor agonistic activity.

  11. Mean platelet volume is decreased in adults with active lupus disease

    Directory of Open Access Journals (Sweden)

    Guillermo Delgado-García

    Full Text Available ABSTRACT Background: Only a few biomarkers are available for assessing disease activity in systemic lupus erythematosus (SLE. Mean platelet volume (MPV has been recently studied as an inflammatory biomarker. It is currently unclear whether MPV may also play a role as a biomarker of disease activity in adult patients with SLE. Objective: We investigated the association between MPV and disease activity in adult patients with SLE. Methods: In this retrospective study, we compared two groups of adult patients divided according to disease activity (36 per group. Subjects were age- and gender-matched. Results: MPV was significantly decreased with respect to those of inactive patients (7.16 ± 1.39 vs. 8.16 ± 1.50, p = 0.005. At a cutoff level of 8.32 fL, MPV has a sensitivity of 86% and a specificity of 41% for the detection of disease activity. A modest positive correlation was found between MPV and albumin (r = 0.407, p = 0.001, which in turn is inversely associated with disease activity. Conclusions: In summary, MPV is decreased in adult patients with active lupus disease, and positively correlated with albumin, another biomarker of disease activity. Prospective studies are needed to evaluate the prognostic value of this biomarker.

  12. [The effect of electromagnetic waves of very high frequency of molecular spectra of radiation and absorption of nitric oxide on the functional activity of platelets].

    Science.gov (United States)

    Kirichuk, V F; Maĭborodin, A V; Volin, M V; Krenitskiĭ, A P; Tupikin, V D

    2001-01-01

    A study was made of the effect of electromagnetic EMI MMD-fluctuation on the frequencies of molecular spectra of radiation, and nitric oxide absorption under in vitro conditions on the functional activity of platelets in patients with unstable angina pectoris, with the help of a specially created generator. At amplitude-modulated and continuous modes of EMI MMD-irradiation of platelet-rich plasma for 5, 15 and 30 min the platelet functional activity decreases, which was shown up in reduction of their activation and fall of aggregative ability. The degree, to which platelet functional activity was inhibited, depended on the mode of irradiation and on duration of EMI MMD effect. The most obvious changes in platelet activation and in their readiness to aggregative response were observed at a continuous mode of irradiation within a 15 min interval.

  13. The influence of conjugates isolated from Matricaria chamomilla L. on platelets activity and cytotoxicity.

    Science.gov (United States)

    Bijak, Michał; Saluk, Joanna; Tsirigotis-Maniecka, Marta; Komorowska, Halina; Wachowicz, Barbara; Zaczyńska, Ewa; Czarny, Anna; Czechowski, Franciszek; Nowak, Paweł; Pawlaczyk, Izabela

    2013-10-01

    Cardiovascular diseases (CVD) remain the principal cause of death in both advanced and developing countries of the world. Blood platelets are involved in the pathogenesis of atherosclerosis and thrombosis. Platelet adhesion and aggregation are critical events that occur in unstable coronary syndromes. The current research is focused on the role of polysaccharide-polyphenolic conjugates isolated from chamomile (Matricaria chamomilla L.) at concentrations of 10, 25, 50 and 100 μg/mL on blood platelets (obtained from healthy donors and from patients received combined anti-platelet therapy complex with clopidogrel and acetylsalicylic acid) aggregation and experimentally induced cell toxicity. The treatment of PRP obtained from healthy donors with polyphenolic-polysaccharide conjugates from M. chamomilla (L.) (MC) resulted in a dose-dependent, decrease of platelet aggregation induced by multiple agonists (ADP, collagen and arachidonic acid). In this study we also observed that the MC reduced platelet aggregation in PRP obtained from patients with cardiovascular disorders. The result of testing the MC on human blood platelets, mouse fibroblast cultures L929 and human lung cells A549 did not show any cytotoxicity effects. Compounds obtained from M. chamomilla L. are potential composite to the development of a new anti-platelet agent, which could be an alternative to the currently used anti-platelet drugs.

  14. Mean platelet volume and mean platelet volume/platelet count ratio ...

    African Journals Online (AJOL)

    Amira M. Elsayed

    2016-03-30

    Mar 30, 2016 ... Abstract The mean platelet volume (MPV) is a laboratory marker associated with platelet func- tion and activity. .... the first 24 h of presentation to the emergency department. Severity of ..... J Neurol Neurosurg Psychiatry.

  15. Platelet activating factor-induced expression of p21 is correlated with histone acetylation

    Science.gov (United States)

    Damiani, Elisabetta; Puebla-Osorio, Nahum; Lege, Bree M.; Liu, Jingwei; Neelapu, Sattva S.; Ullrich, Stephen E.

    2017-01-01

    Ultraviolet (UV)-irradiated keratinocytes secrete the lipid mediator of inflammation, platelet-activating factor (PAF). PAF plays an essential role in UV-induced immune suppression and skin cancer induction. Dermal mast cell migration from the skin to the draining lymph nodes plays a prominent role in activating systemic immune suppression. UV-induced PAF activates mast cell migration by up-regulating mast cell CXCR4 surface expression. Recent findings indicate that PAF up-regulates CXCR4 expression via histone acetylation. UV-induced PAF also activates cell cycle arrest and disrupts DNA repair, in part by increasing p21 expression. Do epigenetic alterations play a role in p21 up-regulation? Here we show that PAF increases Acetyl-CREB-binding protein (CBP/p300) histone acetyltransferase expression in a time and dose-dependent fashion. Partial deletion of the HAT domain in the CBP gene, blocked these effects. Chromatin immunoprecipitation assays indicated that PAF-treatment activated the acetylation of the p21 promoter. PAF-treatment had no effect on other acetylating enzymes (GCN5L2, PCAF) indicating it is not a global activator of histone acetylation. This study provides further evidence that PAF activates epigenetic mechanisms to affect important cellular processes, and we suggest this bioactive lipid can serve as a link between the environment and the epigenome. PMID:28157211

  16. The inflammatory and tumor-promoting sesquiterpene lactone, thapsigargin, activates platelets by selective mobilization of calcium as shown by protein phosphorylations

    DEFF Research Database (Denmark)

    Thastrup, Ole; Linnebjerg, H; Bjerrum, P J

    1987-01-01

    , raised cytoplasmic free calcium level and phosphorylation of platelet proteins was examined in platelet-rich plasma and washed platelet suspension. In contrast to A23187 and thrombin, the platelet activation induced by thapsigargin developed slowly, with maximal response obtained after 2-3 min. Both...... obtained by stimulation of the passive calcium transport through specific channels. These thapsigargin-sensitive channels should predominantly be located in the membranes of intracellular calcium stores rather than in the plasma membrane, because removal of extracellular calcium by EGTA had only...

  17. Effects of platelet-activating factor on the interaction of Trypanosoma cruzi with Rhodnius prolixus.

    Science.gov (United States)

    Zimmermann, Luciana T; Folly, Evelize; Gomes, Marta T; Alviano, Daniela S; Alviano, Celuta S; Silva-Filho, Fernando C; Atella, Geórgia C; Lopes, Angela H

    2011-06-01

    We investigated the effects of platelet-activating factor (PAF) on the interaction of Trypanosoma cruzi with Rhodnius prolixus. The parasites (epimastigotes) were treated with PAF and/or WEB 2086 (PAF antagonist) for 1 h prior to the interaction experiments. PAF stimulated both in vivo and ex vivo interactions between T. cruzi and R. prolixus while WEB 2086 abrogated these effects. PAF-treated epimastigotes also showed an increase in surface negativity and in the amount of surface sialic acid. Neither of these effects was observed when the epimastigotes were treated with neuraminidase following PAF treatment. In the ex vivo interaction experiments, the number of epimastigotes bound to the midguts of the insects was reduced when the epimastigotes had been treated with neuraminidase. We conclude that PAF modulates the interaction of T. cruzi with R. prolixus by altering the amount of sialyl residues at the surface of the parasite.

  18. Creation of reversed phase high-performance liquid chromatographic technique to assay platelet-activating factor

    Institute of Scientific and Technical Information of China (English)

    杨云梅; 曹红翠; 徐哲荣; 陈晓明

    2004-01-01

    Objective: To establish a new assay for platelet-activating factor (PAF), to compare it with bio-assay; and to discuss its significance in some elderly people diseases such as cerebral infarction and coronary heart disease. Methods: To measure PAF levels in 100 controls, 23 elderly patients with cerebral infarction and 65 cases with coronary heart disease by reversed phase high-performance liquid chromatographic technique (rHPLC). Results: rHPLC is more convenient, sensitive, specific, and less confusing, compared with bio-assay. The level of plasma PAF in patients with cerebral infarction was higher than that in the controls (P<0.01), and in patients with coronary heart disease. Conclusion: Detection of PAF with rHPLC is more reliable and more accurate. The new assay has important significance in PAF research.

  19. Creation of reversed phase high-performance liquid chromatographic technique to assay platelet-activating factor

    Institute of Scientific and Technical Information of China (English)

    杨云梅; 曹红翠; 徐哲荣; 陈晓明

    2004-01-01

    Objective: To establish a new assay for platelet-activating factor (PAF), to compare it with bio-assay; and to discuss its significance in some elderly people diseases such as cerebral infarction and coronary heart disease. Methods: To measure PAF levels in 100 controls, 23 elderly patients with cerebral infarction and 65 cases with coronary heart disease by reversed phase high-performance liquid chromatographic technique (rHPLC). Results:rHPLC is more convenient, sensitive,specific, and less confusing, compared with bio-assay. The level of plasma PAF in patients with cerebral infarction was higher than that in the controls (P<0.01), and in patients with coronary heart disease. Conclusion: Detection of PAF with rHPLC is more reliable and more accurate. The new assay has important significance in PAF research.

  20. Hypocoagulant and lipid-lowering effects of dietary n-3 polyunsaturated fatty acids with unchanged platelet activation in rats

    NARCIS (Netherlands)

    Nieuwenhuys, C.M.A.; Béguin, S.; Offermans, R.F.G.; Emeis, J.J.; Hornstra, G.; Heemskerk, J.W.M.

    1998-01-01

    We investigated the effects of dietary polyunsaturated fatty acids (PUFAs) on blood lipids and processes that determine hemostatic potential: platelet activation, coagulation, and fibrinolysis. For 8 to 10 weeks, Wistar rats were fed a high-fat diet containing various amounts (2% to 16%) of n-3 PUFA

  1. Hypocoagulant and lipid-lowering effects of dietary n-3 polyunsaturated fatty acids with unchanged platelet activation in rats

    NARCIS (Netherlands)

    Nieuwenhuys, C.M.A.; Béguin, S.; Offermans, R.F.G.; Emeis, J.J.; Hornstra, G.; Heemskerk, J.W.M.

    1998-01-01

    We investigated the effects of dietary polyunsaturated fatty acids (PUFAs) on blood lipids and processes that determine hemostatic potential: platelet activation, coagulation, and fibrinolysis. For 8 to 10 weeks, Wistar rats were fed a high-fat diet containing various amounts (2% to 16%) of n-3

  2. Megakaryocyte-specific RhoA deficiency causes macrothrombocytopenia and defective platelet activation in hemostasis and thrombosis

    DEFF Research Database (Denmark)

    Pleines, Irina; Hagedorn, Ina; Gupta, Shuchi

    2011-01-01

    of a and dense granules downstream of G(13) and G(q). Furthermore, RhoA was essential for integrin-mediated clot retraction but not for actomyosin rearrangements and spreading of activated platelets on fibrinogen. In vivo, RhoA deficiency resulted in markedly prolonged tail bleeding times but also significant...

  3. Platelet preservation: agitation and containers.

    Science.gov (United States)

    van der Meer, Pieter F; de Korte, Dirk

    2011-06-01

    For platelets to maintain their in vitro quality and in vivo effectiveness, they need to be stored at room temperature with gentle agitation in gas-permeable containers. The mode of agitation affects the quality of the platelets, and a gentle method of agitation, either a circular or a flat bed movement, provides the best results. Tumblers or elliptical agitators induce platelet activation and subsequent damage. As long as the platelets remain in suspension, the agitation speed is not important. Agitation of the platelet concentrates ensures that the platelets are continuously oxygenated, that sufficient oxygen can enter the storage container and that excess carbon dioxide can be expelled. During transportation of platelet concentrates, nowadays over long distances where they are held without controlled agitation, platelets may tolerate a certain period without agitation. However, evidence is accumulating that during the time without agitation, local hypoxia surrounding the platelets may induce irreversible harm to the platelets. Over the decades, more gas-permeable plastics have been used to manufacture platelet containers. The use of different plastics and their influence on the platelet quality both in vitro and in vivo is discussed. The improved gas-permeability has allowed the extension of platelet storage from 3 days in the early 1980s, to currently at least 7 days. In the light of new developments, particularly the introduction of pathogen reduction techniques, the use of platelet additive solutions and the availability of improved automated separators, further (renewed) research in this area is warranted.

  4. Novel anti-bacterial activities of β-defensin 1 in human platelets: suppression of pathogen growth and signaling of neutrophil extracellular trap formation.

    Directory of Open Access Journals (Sweden)

    Bjoern F Kraemer

    2011-11-01

    Full Text Available Human β-defensins (hBD are antimicrobial peptides that curb microbial activity. Although hBD's are primarily expressed by epithelial cells, we show that human platelets express hBD-1 that has both predicted and novel antibacterial activities. We observed that activated platelets surround Staphylococcus aureus (S. aureus, forcing the pathogens into clusters that have a reduced growth rate compared to S. aureus alone. Given the microbicidal activity of β-defensins, we determined whether hBD family members were present in platelets and found mRNA and protein for hBD-1. We also established that hBD-1 protein resided in extragranular cytoplasmic compartments of platelets. Consistent with this localization pattern, agonists that elicit granular secretion by platelets did not readily induce hBD-1 release. Nevertheless, platelets released hBD-1 when they were stimulated by α-toxin, a S. aureus product that permeabilizes target cells. Platelet-derived hBD-1 significantly impaired the growth of clinical strains of S. aureus. hBD-1 also induced robust neutrophil extracellular trap (NET formation by target polymorphonuclear leukocytes (PMNs, which is a novel antimicrobial function of β-defensins that was not previously identified. Taken together, these data demonstrate that hBD-1 is a previously-unrecognized component of platelets that displays classic antimicrobial activity and, in addition, signals PMNs to extrude DNA lattices that capture and kill bacteria.

  5. sup 86 Rb(K) influx and ( sup 3 H)ouabain binding by human platelets: Evidence for beta-adrenergic stimulation of Na-K ATPase activity

    Energy Technology Data Exchange (ETDEWEB)

    Turaihi, K.; Khokher, M.A.; Barradas, M.A.; Mikhailidis, D.P.; Dandona, P. (Royal Free Hospital and School of Medicine, London (England))

    1989-08-01

    Although active transport of potassium into human platelets has been demonstrated previously, there is hitherto no evidence that human platelets have an ouabain-inhibitable Na-K ATPase in their membrane. The present study demonstrates active rubidium (used as an index of potassium influx), {sup 86}Rb(K), influx into platelets, inhibitable by ouabain, and also demonstrates the presence of specific ({sup 3}H)ouabain binding by the human platelet. This {sup 86}Rb(K) influx was stimulated by adrenaline, isoprenaline, and salbutamol, but noradrenaline caused a mild inhibition. Active {sup 86}Rb(K) influx by platelets was inhibited markedly by timolol, mildly by atenolol, but not by phentolamine. Therefore, active {sup 86}Rb(K) influx in human platelets is enhanced by stimulation of beta adrenoceptors of the beta 2 subtype. The platelet may therefore replace the leukocyte in future studies of Na-K ATPase activity. This would be a considerable advantage in view of the ease and rapidity of preparation of platelets.

  6. Omic approaches to quality biomarkers for stored platelets: are we there yet?

    Science.gov (United States)

    Kulkarni, Sandhya; Kannan, Meganathan; Atreya, Chintamani D

    2010-07-01

    At present, there is no single biomarker that serves as the "gold standard" predictive of the quality of stored platelets used for transfusion. Some of the measurable features of platelets such as morphology, biochemical status, physiologic response to osmotic stress and agonist-induced changes, and measurement of process-associated activation indicators of platelets are considered useful in assessing the in vitro quality of stored platelets. Such in vitro measurements combined with in vivo survival estimations using radiolabeled platelets in healthy volunteers provide reasonable estimates of in vivo platelet function after transfusion. Thus, the current practice of estimating the quality and functional aspects of ex vivo stored platelets involves utilization of a battery of tests that dates back to pre-omic era. On the other hand, during the last decade, seminal discoveries have been made in platelet molecular and cell biology by using "omic"-based approaches such as proteomics, genomics, and transcriptomics. Can we mobilize some of these discoveries toward developing reliable quality biomarkers for stored platelets? To address this topic, we briefly review current practices and provide insights into some of the omic approaches that could be helpful in identifying quality storage biomarkers of platelets in the near future. We also briefly discuss here some of the challenges in using proteomic approaches and advantages of using one of the transcriptomics approaches toward platelet biomarker development.

  7. The changes of blood platelet activation in breast cancer patients before surgery, after surgery, and in various phases of the chemotherapy.

    Science.gov (United States)

    Kedzierska, Magdalena; Czernek, Urszula; Szydłowska-Pazera, Katarzyna; Potemski, Piotr; Piekarski, Janusz; Jeziorski, Arkadiusz; Olas, Beata

    2013-01-01

    Blood platelets from patients with cancer (before or after the surgery) exhibit a variety of qualitative abnormalities. Different anti-cancer drugs may also induce the oxidative/nitrative stress in blood platelets and change their hemostatic properties. The aim of our study was to explain the effect of superoxide anion radicals ([Formula: see text]) production on hemostatic properties of blood platelets (activated by a strong physiological agonist - thrombin) from breast cancer patients before the surgery, after the surgery, and after various phases (I-IV) of chemotherapy (doxorubicin and cyclophosphamide). Patients were hospitalized in the Department of Oncological Surgery and at the Department of Chemotherapy, Medical University of Lodz, Poland. We measured the platelet aggregation as the marker of hemostatic activity of blood platelets. We observed an increase of [Formula: see text] in thrombin-activated blood platelets from patients with breast cancer (before or after the surgery and after various phases of the chemotherapy) compared to the healthy group. Our other experiments demonstrated that aggregation (induced by thrombin) of blood platelets from patients with breast cancer before the surgery, after the surgery, and after various phases of the chemotherapy differs from aggregation of platelets obtained from healthy volunteers. Moreover, our results showed the correlation between the [Formula: see text] generation and changes of platelet aggregation in breast cancer patients before the surgery, after the surgery, and after the chemotherapy (I and IV phases). Considering the data presented in this study, we suggest that the production of [Formula: see text] in blood platelets (activated by thrombin) obtained from breast cancer patients may induce the changes of platelet aggregation, which may contribute in thrombosis in these patients.

  8. Minimizing Platelet Activation-Induced Clogging in Deterministic Lateral Displacement Arrays for High-Throughput Capture of Circulating Tumor Cells

    Science.gov (United States)

    D'Silva, Joseph; Loutherback, Kevin; Austin, Robert; Sturm, James

    2013-03-01

    Deterministic lateral displacement arrays have been used to separate circulating tumor cells (CTCs) from diluted whole blood at flow rates up to 10 mL/min (K. Loutherback et al., AIP Advances, 2012). However, the throughput is limited to 2 mL equivalent volume of undiluted whole blood due to clogging of the array. Since the concentration of CTCs can be as low as 1-10 cells/mL in clinical samples, processing larger volumes of blood is necessary for diagnostic and analytical applications. We have identified platelet activation by the micro-post array as the primary cause of this clogging. In this talk, we (i) show that clogging occurs at the beginning of the micro-post array and not in the injector channels because both acceleration and deceleration in fluid velocity are required for clogging to occur, and (ii) demonstrate how reduction in platelet concentration and decrease in platelet contact time within the device can be used in combination to achieve a 10x increase in the equivalent volume of undiluted whole blood processed. Finally, we discuss experimental efforts to separate the relative contributions of contact activated coagulation and shear-induced platelet activation to clogging and approaches to minimize these, such as surface treatment and post geometry design.

  9. Modifications produced by selective inhibitors of cyclooxygenase and ultra low dose aspirin on platelet activity in portal hypertension

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    AIM: To study the mechanism involved in the potentially beneficial effect of ultra low dose aspirin (ULDA) in prehepatic portal hypertension, rats were pretreated with selective COX 1 or 2 inhibitors (SC-560 or NS-398 respectively), and subsequently injected with ULDA or placebo.METHODS: Portal hypertension was induced by portal vein ligation. Platelet activity was investigated with an in-vivo model of laser induced thrombus production in mesenteric circulation and induced hemorrhagic time (IHT). Platelet aggregation induced by ADP and dosing of prostanoid products 6-keto-PGF1α, TXB2, PGE2 and LTB4 were also performed.RESULTS: The portal hypertensive group receiving a placebo showed a decreased in vivo platelet activity with prolonged IHT, an effect that was normalized by ULDA. SC-560 induced a mild antithrombotic effect in the normal rats, and an unmodified effect of ULDA. NS-398 had a mild prothrombotic action in portal hypertensive rats, similar to ULDA, but inhibited a further effect when ULDA was added. An increased 6-keto-PGF1α was observed in portal hypertensive group that was normalised after ULDA administration. TXA2 level after ULDA, remained unchanged.CONCLUSION: These results suggest that the effect of ULDA on platelet activity in portal hypertensive rats,could act through a COX 2 pathway more than the COX 1,predominant for aspirin at higher doses.

  10. The value of flow cytometry in the measurement of platelet activation and aggregation in human immunodeficiency virus infection.

    Science.gov (United States)

    Nkambule, Bongani B; Davison, Glenda; Ipp, Hayley

    2015-01-01

    Human immunodeficiency deficiency virus (HIV) infection is associated with chronic inflammation and an increased risk of thrombotic events. Activated platelets (PLTs) play an important role in both thrombosis and inflammation, and HIV has been shown to induce PLT activation by both direct and indirect mechanisms. P-selectin (CD62P) is a well-described marker of PLT activation, and PLT glycoprotein (GP) IV (CD36) has been identified as a marker of PLT aggregation. Data on PLT function in the context of HIV infection remain inconclusive. Laboratory techniques, such as flow cytometry, enable the assessment of PLTs in their physiological state and environment, with minimal artifactual in vitro activation and aggregation. In this study, we describe a novel flow cytometry PLT assay, which enabled the measurement of PLT function in HIV infection. Forty-one antiretroviral-naïve HIV-positive individuals and 41 HIV-negative controls were recruited from a clinic in the Western Cape. Platelet function was evaluated by assessing the response of platelets to adenosine diphosphate (ADP) at two concentrations (0.04 mM, 0.2 mM). The percentage expression and mean fluorescence intensity (MFI) of CD62P and CD36 was used to evaluate platelet function. These were then correlated with platelet (PLT) count; CD4 count; % CD38/8; viral load and D-dimers. The % CD62P levels were higher in HIV-positive patients (HIV % CD62P 11.33[5.96-29.36] vs. control 2.48[1.56-6.04]; p infection. We were able to show that, although PLTs are significantly activated in HIV compared to uninfected controls, they retain their functional capacity.

  11. Gasotransmitters and platelets.

    Science.gov (United States)

    Truss, Nicola J; Warner, Timothy D

    2011-11-01

    Platelets are essential to prevent blood loss and promote wound healing. Their activation comprises of several complex steps which are regulated by a range of mediators. Over the last few decades there has been intense interest in a group of gaseous mediators known as gasotransmitters; currently comprising nitric oxide (NO), carbon monoxide (CO) and hydrogen sulphide (H(2)S). Here we consider the action of gasotransmitters on platelet activity. NO is a well established platelet inhibitor which mediates its effects predominantly through activation of soluble guanylyl cyclase leading to a decrease in intraplatelet calcium. More recently CO has been identified as a gasotransmitter with inhibitory actions on platelets; CO acts through the same mechanism as NO but is less potent. The in vivo and platelet functions of the most recently identified gasotransmitter, H(2)S, are still the subject of investigations, but they appear generally inhibitory. Whilst there is evidence for the individual action of these mediators, it is also likely that combinations of these mediators are more relevant regulators of platelets. Furthermore, current evidence suggests that these mediators in combination alter the production of each other, and so modify the circulating levels of gasotransmitters. The use of gasotransmitters as therapeutic agents is also being explored for a range of indications. In conclusion, the importance of NO in the regulation of vascular tone and platelet activity has long been understood. Other gasotransmitters are now establishing themselves as mediators of vascular tone, and recent evidence suggests that these other gasotransmitters may also modulate platelet function.

  12. Scintigraphic evaluation of early osteoblastic activity in extraction sockets treated with platelet-rich plasma.

    Science.gov (United States)

    Gürbüzer, Bahadir; Pikdöken, Levent; Urhan, Muammer; Süer, B Tolga; Narin, Yavuz

    2008-12-01

    The aim of this study was to investigate the early effect of platelet-rich plasma (PRP) on osteoblastic activity during the healing process of soft tissue impacted mandibular third molar extraction sockets by means of bone scintigraphy. Twelve patients with bilaterally soft tissue impacted mandibular third molars were included in the study. The impacted right and left mandibular third molars were surgically extracted in the same session. PRP was administered randomly into the extraction sockets in the study (S) group whereas the extraction sockets in the control (C) group were left without PRP treatment. Scintigrams were obtained in the first and fourth weeks after surgery to evaluate the osteoblastic activity within extraction sockets in both groups. Scintigraphic findings of postoperative first and fourth weeks did not show significantly increased osteoblastic activity between S group and C group (P > .05). However, the osteoblastic activity in both groups significantly increased in postoperative week 4 in comparison to week 1 (P third molar extraction sockets failed to increase the osteoblastic activity in postsurgical weeks 1 and 4 in comparison to non-PRP-treated sockets.

  13. Role of platelet-activating factor in pathogenesis of acute pancreatitis

    Institute of Scientific and Technical Information of China (English)

    Li-Rong Liu; Shi-Hai Xia

    2006-01-01

    Platelet-activating factor (PAF) is a potent proinflammatory phospholipid mediator that belongs to a family of biologically active, structurally related alkyl phosphoglycerides with diverse pathological and physiological effects. This bioactive phospholipid mediates processes as diverse as wound healing,physiological inflammation, angiogenesis, apoptosis,reproduction and long-term potentiation. PAF acts by binding to a specific G protein-coupled receptor to activate multiple intracellular signaling pathways.Since most cells both synthesize and release PAF and express PAF receptors, PAF has potent biological actions in a broad range of cell types and tissues.Inappropriate activation of this signaling pathway is associated with many diseases in which inflammation is thought to be one of the underlying features. Acute pancreatitis (AP) is a common inflammatory disease.The onset of AP is pancreatic autodigestion mediated by abnormal activation of pancreatic enzyme caused by multiple agents, which subsequently induce pancreatic and systemic inflammatory reactions. A number of experimental pancreatitis and clinical trials indicate that PAF does play a critical role in the pathogenesis of AP. Administration of PAF receptor antagonist can significantly reduce local and systemic events that occur in AP. This review focuses on the aspects that are more relevant to the pathogenesis of AP.

  14. Platelet activation and dysfunction in a large-animal model of traumatic brain injury and hemorrhage

    DEFF Research Database (Denmark)

    Sillesen, Martin; Johansson, Pär I; Rasmussen, Lars S

    2013-01-01

    Traumatic brain injury (TBI) and hemorrhage are the leading causes of trauma-related mortality. Both TBI and hemorrhage are associated with coagulation disturbances, including platelet dysfunction. We hypothesized that platelet dysfunction could be detected early after injury, and that this dysfu...

  15. The inhibitory activity of ginsenoside Rp4 in adenosine diphosphate-induced platelet aggregation

    Directory of Open Access Journals (Sweden)

    Young-Min Son

    2017-01-01

    Conclusion: G-Rp4 significantly inhibited ADP-induced platelet aggregation and this is mediated via modulating the intracellular signaling molecules. These results indicate that G-Rp4 could be a potential candidate as a therapeutic agent against platelet-related cardiovascular diseases.

  16. Rhodocytin (aggretin) activates platelets lacking alpha(2)beta(1) integrin, glycoprotein VI, and the ligand-binding domain of glycoprotein Ibalpha

    DEFF Research Database (Denmark)

    Bergmeier, W; Bouvard, D; Eble, J A

    2001-01-01

    Although alpha(2)beta(1) integrin (glycoprotein Ia/IIa) has been established as a platelet collagen receptor, its role in collagen-induced platelet activation has been controversial. Recently, it has been demonstrated that rhodocytin (also termed aggretin), a snake venom toxin purified from the v...

  17. Isolation of bovine platelet cationic proteins which inhibit the surface-mediated activation of factor XII and prekallikrein.

    Science.gov (United States)

    Kodama, K; Kato, H; Iwanaga, S

    1985-01-01

    A possible role of bovine platelets in the surface-mediated activation of Factor XII and prekallikrein was studied, using the contact system reconstituted with the purified proteins from bovine plasma. The washed platelets before and after aggregation by ADP, thrombin or collagen did not show any ability to trigger or accelerate the activation of Factor XII and prekallikrein. On the contrary, these aggregates showed a potent inhibitory activity on the activation of those zymogens triggered by kaolin, amylose sulfate and sulfatide. The inhibitory substances from the supernatant of the thrombin-induced aggregates were separated into two major fractions, a low affinity fraction and a high affinity fraction, on a heparin-Sepharose column. The high affinity protein was identified as platelet factor 4, based on the amino acid composition. From the low affinity fraction, a beta-thromboglobulin (beta-TG)-like substance and three kinds of unknown proteins, named LA1, LA2, and LA3, were isolated by gel-filtration on a column of Sephadex G-100 or Sephadex G-75 followed by chromatography on a column of Mono S. The molecular weights of LA1, LA2, and LA3 were estimated to be 35,000, 26,000, and 11,000, respectively, on SDS-PAGE. LA2 was identified as a carbohydrate-less LA1, as judged from the amino acid composition and carbohydrate content. The inhibitory activities of these five cationic proteins on the activation of Factor XII and prekallikrein mediated with amylose sulfate, sulfatide and kaolin were different from each other. In the case of kaolin-mediated activation, LA3 was the most potent inhibitor, while platelet factor 4 and beta-TG-like substance did not show any significant inhibitory activity. Moreover, the inhibitory activities of all the cationic proteins were not correlated with their anti-heparin activities. Since these proteins were rapidly liberated from platelets by the action of the stimulants, the present results demonstrate a negative role of platelets in

  18. CdTe quantum dots induce activation of human platelets: implications for nanoparticle hemocompatibility

    Science.gov (United States)

    Samuel, Stephen P; Santos-Martinez, Maria J; Medina, Carlos; Jain, Namrata; Radomski, Marek W; Prina-Mello, Adriele; Volkov, Yuri

    2015-01-01

    New nanomaterials intended for systemic administration have raised concerns regarding their biocompatibility and hemocompatibility. Quantum dots (QD) nanoparticles have been used for diagnostics, and recent work suggests their use for in vivo molecular and cellular imaging. However, the hemocompatibility of QDs and their constituent components has not been fully elucidated. In the present study, comprehensive investigation of QD–platelet interactions is presented. These interactions were shown using transmission electron microscopy. The effects of QDs on platelet function were investigated using light aggregometry, quartz crystal microbalance with dissipation, flow cytometry, and gelatin zymography. Platelet morphology was also analyzed by phase-contrast, immunofluorescence, atomic-force and transmission electron microscopy. We show that the QDs bind to platelet plasma membrane with the resultant upregulation of glycoprotein IIb/IIIa and P-selectin receptors, and release of matrix metalloproteinase-2. These findings unravel for the first time the mechanism of functional response of platelets to ultrasmall QDs in vitro. PMID:25897218

  19. Effect of simvastatin combined amlodipine besylate on blood rheology and platelet activation in elderly patients with hypertension complicated with hyperlipemia

    Institute of Scientific and Technical Information of China (English)

    Ming-Zheng Jiang; Li Qiong; Hui Liu

    2016-01-01

    Objective:To investigate the effect of simvastatin combined amlodipine besylate on blood rheology and platelet activation in elderly patients with hypertension complicated with hyperlipemia.Methods: A total of 200 elderly patients with hypertension complicated with hyperlipemia were divided into hypertension group (n=64), hyperlipemia group (n=71) and combined (hypertension complicated with hyperlipemia) group (n=65). And alternate period health check-up 100 cases were selected as control group. The hypertension group was treated with amlodipine besylate monotherapy, hyperlipidemia group with simvastatin monotherapy, combined group received simvastatin combined with amlodipine besylate treatment, patients of three groups were treated for 12 weeks. Blood rheology and platelet activation before and after treatment were compared.Results: After treatment, blood pressure was significantly lower than that before treatment in hypertension and combined group (P<0.05), and the combined group reduced more significantly (P<0.05), blood fat was significantly lower than that before treatment in hyperlipemia and combined group (P<0.05), and combined group reduced more significantly (P<0.05); Before treatment, indexes of blood rheology (high shear whole blood viscosity, low shear whole blood viscosity, plasma viscosity, fibrinogen and platelet activation index (CD62p and CD63) of three groups were significantly higher than those in control group (P<0.05), and the combined group was increased more significantly than hypertension and hyperlipidemia group (P<0.05); After treatment, blood rheology (high shear whole blood viscosity, low shear whole blood viscosity, plasma viscosity, fibrinogen) and platelet activation index (CD62p and CD63) of hyperlipidemia group and combined group were significantly lower than before treatment (P<0.05), and the reduction combined group were more significant in amplitude (P<0.05).Conclusions: Simvastatin combined amlodipine besylate therapy can

  20. Role of focal adhesion tyrosine kinases in GPVI-dependent platelet activation and reactive oxygen species formation.

    Directory of Open Access Journals (Sweden)

    Naadiya Carrim

    Full Text Available We have previously shown the presence of a TRAF4/p47phox/Hic5/Pyk2 complex associated with the platelet collagen receptor, GPVI, consistent with a potential role of this complex in GPVI-dependent ROS formation. In other cell systems, NOX-dependent ROS formation is facilitated by Pyk2, which along with its closely related homologue FAK are known to be activated and phosphorylated downstream of ligand binding to GPVI.To evaluate the relative roles of Pyk2 and FAK in GPVI-dependent ROS formation and to determine their location within the GPVI signaling pathway.Human and mouse washed platelets (from WT or Pyk2 KO mice were pre-treated with pharmacological inhibitors targeting FAK or Pyk2 (PF-228 and Tyrphostin A9, respectively and stimulated with the GPVI-specific agonist, CRP. FAK, but not Pyk2, was found to be essential for GPVI-dependent ROS production and aggregation. Subsequent human platelet studies with PF-228 confirmed FAK is essential for GPVI-mediated phosphatidylserine exposure, α-granule secretion (P-selectin (CD62P surface expression and integrin αIIbβ3 activation. To determine the precise location of FAK within the GPVI pathway, we analyzed the effect of PF-228 inhibition in CRP-stimulated platelets in conjunction with immunoprecipitation and pulldown analysis to show that FAK is downstream of Lyn, Spleen tyrosine kinase (Syk, PI3-K and Bruton's tyrosine kinase (Btk and upstream of Rac1, PLCγ2, Ca2+ release, PKC, Hic-5, NOX1 and αIIbβ3 activation.Overall, these data suggest a novel role for FAK in GPVI-dependent ROS formation and platelet activation and elucidate a proximal signaling role for FAK within the GPVI pathway.

  1. Assessment of the influence of the inflammatory process on the activation of blood platelets and morphological parameters in patients with ulcerative colitis (colitis ulcerosa

    Directory of Open Access Journals (Sweden)

    Beata Polińska

    2011-04-01

    Full Text Available Ulcerative colitis (colitis ulcerosa is a non-specific inflammatory bowel disease of unknown etiology. Thesymptoms which are observed in the course of ulcerative colitis are: an increase in the number of leukocytes andblood platelets, an increase in the concentration of IL-6 and anemia. Blood platelets are the key element, linkingthe processes of hemostasis, inflammation and the repair of damaged tissues. Activation of blood platelets is connectedwith changes in their shape and the occurrence of the reaction of release. P-selectin appears on the surfacesof activated blood platelets and the concentration level of soluble P-selectin increases in the blood plasma. The aimof this study was to define whether the increased number of blood platelets in patients with ulcerative colitisaccompanies changes in their activation and morphology. A total of 16 subjects with ulcerative colitis and 32healthy subjects were studied. Mean platelet count, morphological parameters of platelets and MPC were measuredusing an ADVIA 120 hematology analyzer. Concentrations of sP-selectin and IL-6 in serum were marked byimmunoassay (ELISA. MPC, concentration of sP-selectin and IL-6 were significantly higher in subjects with ulcerativecolitis compared to those in the healthy group. There was a decrease of MPV in patients with ulcerativecolitis, which is statistically significant. Chronic inflammation in patients with ulcerative colitis causes an increase inthe number of blood platelets, a change in their morphology and activation. Decreased MPV value reflects activationand the role blood platelets play in the inflammatory process of the mucous membrane of the colon. A highconcentration of sP-selectin, which is a marker of blood platelet activation, demonstrates their part in the inflammatoryprocess. The increase in the concentration of sP-selectin correlated positively with the increase in concentrationof IL-6. This is why it may be a useful marker of the activity of

  2. Effects of fused hirudin on activity of thrombin and function of platelets

    Institute of Scientific and Technical Information of China (English)

    SHEN Li; CHEN Shao-ping; CAI Zai-long; YANG Sheng-sheng; QIN Yong-wen

    2005-01-01

    Objective: To investigate whether fused hirudin peptide has both antithrombin and antiplatelet functions. Methods: The core region of fused hirudin was the C-terminal tail of hirudin(hirudin53-64),which could bind to the anion binding exosite (ABE) of thrombin.Arg-Pro-Pro-Gly-Phe(RPPGF) amino acid sequence,a metabolite of bradykinin,was added to the N-terminus of hirudin53-64.It bound to the active site of thrombin.Additionally,Arg-Gly-Asp(RGD)amino acid sequence,an inibitor of glycoprotein Ⅱb/Ⅲa( GP Ⅱb/Ⅲa) receptor,was linked to C-terminus of hirudin53-64.This 26-animo acid-fused hirudin peptide was artificially synthesized,purified and analysed. Results: Fused hirudin peptide significantly lengthened the activated partial thromboplastin time(APTT),thrombin time(TT)and prothrombin time(PT) and inhibited the amidolytic activity of thrombin.The ADP-induced platelet aggregation was markedly inhibited by fused hirudin peptide. Conclusion: Fused hirudin peptide has activity of antithrombin as well as antiplatelet.Therefore bifunctional anticoagulation peptide has capacity to target various components of haemostatic process and may become more powerful antithrombosis agent.

  3. Flavanols and Platelet Reactivity

    Directory of Open Access Journals (Sweden)

    Debra A. Pearson

    2005-01-01

    Full Text Available Platelet activity and platelet-endothelial cell interactions are important in the acute development of thrombosis, as well as in the pathogenesis of cardiovascular disease. An increasing number of foods have been reported to have platelet-inhibitory actions, and research with a number of flavanol-rich foods, including, grape juice, cocoa and chocolate, suggests that these foods may provide some protection against thrombosis. In the present report, we review a series of in vivo studies on the effects of flavanol-rich cocoa and chocolate on platelet activation and platelet-dependent primary hemostasis. Consumption of flavanol-rich cocoa inhibited several measures of platelet activity including, epinephrine- and ADP-induced glycoprotein (GP IIb/IIIa and P-Selectin expression, platelet microparticle formation, and epinephrine-collagen and ADP-collagen induced primary hemostasis. The epinephrine-induced inhibitory effects on GP IIb/IIIa and primary hemostasis were similar to, though less robust than those associated with the use of low dose (81 mg aspirin. These data, coupled with information from other studies, support the concept that flavanols present in cocoa and chocolate can modulate platelet function through a multitude of pathways.

  4. Synthesis of Analogues of Gingerol and Shogaol, the Active Pungent Principles from the Rhizomes of Zingiber officinale and Evaluation of Their Anti-Platelet Aggregation Effects

    Directory of Open Access Journals (Sweden)

    Hung-Cheng Shih

    2014-03-01

    Full Text Available The present study was aimed at discovering novel biologically active compounds based on the skeletons of gingerol and shogaol, the pungent principles from the rhizomes of Zingiber officinale. Therefore, eight groups of analogues were synthesized and examined for their inhibitory activities of platelet aggregation induced by arachidonic acid, collagen, platelet activating factor, and thrombin. Among the tested compounds, [6]-paradol (5b exhibited the most significant anti-platelet aggregation activity. It was the most potent candidate, which could be used in further investigation to explore new drug leads.

  5. The P2Y(12 antagonists, 2MeSAMP and cangrelor, inhibit platelet activation through P2Y(12/G(i-dependent mechanism.

    Directory of Open Access Journals (Sweden)

    Binggang Xiang

    Full Text Available BACKGROUND: ADP is an important physiological agonist that induces integrin activation and platelet aggregation through its receptors P2Y(1 (Gα(q-coupled and P2Y(12 (Gα(i-coupled. P2Y(12 plays a critical role in platelet activation and thrombosis. Adenosine-based P2Y(12 antagonists, 2-methylthioadenosine 5'-monophosphate triethylammonium salt hydrate (2MeSAMP and Cangrelor (AR-C69931MX have been widely used to demonstrate the role of P2Y(12 in platelet function. Cangrelor is being evaluated in clinical trials of thrombotic diseases. However, a recent study reported that both 2MeSAMP and Cangrelor raise intra-platelet cAMP levels and inhibit platelet aggregation through a P2Y(12-independent mechanism. METHODOLOGY/PRINCIPAL FINDINGS: The present work, using P2Y(12 deficient mice, sought to clarify previous conflicting reports and to elucidate the mechanisms by which 2MeSAMP and Cangrelor inhibit platelet activation and thrombosis. 2MeSAMP and Cangrelor inhibited aggregation and ATP release of wild-type but not P2Y(12 deficient platelets. 2MeSAMP and Cangrelor neither raised intracellular cAMP concentrations nor induced phosphorylation of vasodilator-stimulated phosphoprotein (VASP in washed human or mouse platelets. Furthermore, unlike the activators (PGI(2 and forskolin of the cAMP pathway, 2MeSAMP and Cangrelor failed to inhibit Ca(2+ mobilization, Akt phosphorylation, and Rap1b activation in P2Y(12 deficient platelets. Importantly, while injection of Cangrelor inhibited thrombus formation in a FeCl(3-induced thrombosis model in wild-type mice, it failed to affect thrombus formation in P2Y(12 deficient mice. CONCLUSIONS: These data together demonstrate that 2MeSAMP and Cangrelor inhibit platelet function through the P2Y(12-dependent mechanism both in vitro and in vivo.

  6. Platelet mimicry

    DEFF Research Database (Denmark)

    Moghimi, Seyed Moein; Hunter, Alan Christy; Peer, Dan

    2016-01-01

    Here we critically examine whether coating of nanoparticles with platelet membranes can truly disguise them against recognition by elements of the innate immune system. We further assess whether the "cloaking technology" can sufficiently equip nanoparticles with platelet-mimicking functionalities...

  7. Platelet Count

    Science.gov (United States)

    ... their spleen removed surgically Use of birth control pills (oral contraceptives) Some conditions may cause a temporary (transitory) increased ... increased platelet counts include estrogen and birth control pills (oral contraceptives). Mildly decreased platelet counts may be seen in ...

  8. Hydroxyl-platelet-activating factor exists in blood of healthy volunteers and periodontal patients

    Directory of Open Access Journals (Sweden)

    Smaragdi Antonopoulou

    2003-01-01

    Full Text Available Periodontal diseases are localized chronic inflammatory conditions of the gingival and underlying bone and connective tissue. Platelet-activating factor (PAF, a potent inflammatory phospholipid mediator that has been previously detected in elevated levels in inflamed gingival tissues, in gingival crevicular fluid and in saliva, is implicated in periodontal disease. Our results from previous studies showed that the biologically active phospholipid detected in gingival crevicular fluid is a hydroxyl-PAF analogue. In this study, hydroxyl-PAF analogue was detected for the first time in human blood derived from patients with chronic periodontitis as well as from periodontally healthy volunteers. The hydroxyl-PAF analogue was purified by high-performance liquid chromatography, detected by biological assays and identified by electrospray analysis. In addition, the quantitative determination of PAF and hydroxyl-PAF analogue (expressed as PAF-like activity showed a statistically significant increase in the ratio of hydroxyl-PAF analogue levels to PAF levels in periodontal patients, suggesting that this bioactive lipid may play a role in oral inflammation.

  9. Marine Benthic Diatoms Contain Compounds Able to Induce Leukemia Cell Death and Modulate Blood Platelet Activity

    Science.gov (United States)

    Prestegard, Siv Kristin; Oftedal, Linn; Coyne, Rosie Theresa; Nygaard, Gyrid; Skjærven, Kaja Helvik; Knutsen, Gjert; Døskeland, Stein Ove; Herfindal, Lars

    2009-01-01

    In spite of the high abundance and species diversity of diatoms, only a few bioactive compounds from them have been described. The present study reveals a high number of mammalian cell death inducing substances in biofilm-associated diatoms sampled from the intertidal zone. Extracts from the genera Melosira, Amphora, Phaeodactylum and Nitzschia were all found to induce leukemia cell death, with either classical apoptotic or autophagic features. Several extracts also contained inhibitors of thrombin-induced blood platelet activation. Some of this activity was caused by a high content of adenosine in the diatoms, ranging from 0.07 to 0.31 μg/mg dry weight. However, most of the bioactivity was adenosine deaminase-resistant. An adenosine deaminase-resistant active fraction from one of the extracts was partially purified and shown to induce apoptosis with a distinct phenotype. The results show that benthic diatoms typically found in the intertidal zone may represent a richer source of interesting bioactive compounds than hitherto recognized. PMID:20098602

  10. Marine Benthic Diatoms Contain Compounds Able to Induce Leukemia Cell Death and Modulate Blood Platelet Activity

    Directory of Open Access Journals (Sweden)

    Lars Herfindal

    2009-11-01

    Full Text Available In spite of the high abundance and species diversity of diatoms, only a few bioactive compounds from them have been described. The present study reveals a high number of mammalian cell death inducing substances in biofilm-associated diatoms sampled from the intertidal zone. Extracts from the genera Melosira, Amphora, Phaeodactylum and Nitzschia were all found to induce leukemia cell death, with either classical apoptotic or autophagic features. Several extracts also contained inhibitors of thrombin-induced blood platelet activation. Some of this activity was caused by a high content of adenosine in the diatoms, ranging from 0.07 to 0.31 μg/mg dry weight. However, most of the bioactivity was adenosine deaminase-resistant. An adenosine deaminase-resistant active fraction from one of the extracts was partially purified and shown to induce apoptosis with a distinct phenotype. The results show that benthic diatoms typically found in the intertidal zone may represent a richer source of interesting bioactive compounds than hitherto recognized.

  11. Thrombopoietin potentiates the protein-kinase-C-mediated activation of mitogen-activated protein kinase/ERK kinases and extracellular signal-regulated kinases in human platelets.

    Science.gov (United States)

    Ezumi, Y; Uchiyama, T; Takayama, H

    1998-12-15

    The thrombopoietin (TPO) receptor is expressed in the megakaryocytic lineage from late progenitors to platelets. We investigated the effect of TPO on the extracellular signal-regulated kinase (ERK) activation pathway in human platelets. TPO by itself did not activate ERK1, ERK2 and protein kinase C (PKC), whereas TPO directly enhanced the PKC-dependent activation of ERKs induced by other agonists including thrombin and phorbol esters, without affecting the PKC activation by those agonists. TPO did not activate the mitogen-activated protein kinase/ERK kinases, MEK1 and MEK2, but activated Raf-1 and directly augmented the PKC-mediated MEK activation, suggesting that TPO primarily potentiates the ERK pathway through regulating MEKs or upstream steps of MEKs including Raf-1. The MEK inhibitor PD098059 failed to affect not only thrombin-induced or phorbol ester-induced aggregation, but also potentiation of aggregation by TPO, denying the primary involvement of ERKs and MEKs in those events. ERKs and MEKs were located mainly in the detergent-soluble/non-cytoskeletal fractions. ERKs but not MEKs were relocated to the cytoskeleton following platelet aggregation and actin polymerization. These data indicate that TPO synergizes with other agonists in the ERK activation pathway of platelets and that this synergy might affect functions of the cytoskeleton possibly regulated by ERKs.

  12. Clinical Safety of a High Dose of Phycocyanin-Enriched Aqueous Extract from Arthrospira (Spirulina) platensis: Results from a Randomized, Double-Blind, Placebo-Controlled Study with a Focus on Anticoagulant Activity and Platelet Activation.

    Science.gov (United States)

    Jensen, Gitte S; Drapeau, Cassandra; Lenninger, Miki; Benson, Kathleen F

    2016-07-01

    The goal for this study was to evaluate safety regarding anticoagulant activity and platelet activation during daily consumption of an aqueous cyanophyta extract (ACE), containing a high dose of phycocyanin. Using a randomized, double-blind, placebo-controlled study design, 24 men and women were enrolled after informed consent, and consumed either ACE (2.3 g/day) or placebo daily for 2 weeks. The ACE dose was equivalent to ∼1 g phycocyanin per day, chosen based on the highest dose Generally Recognized as Safe (GRAS) by the U.S. Food and Drug Administration. Consuming ACE did not alter markers for platelet activation (P-selectin expression) or serum P-selectin levels. No changes were seen for activated partial thromboplastin time, thrombin clotting time, or fibrinogen activity. Serum levels of aspartate transaminase (AST) showed a significant reduction after 2 weeks of ACE consumption (P < .001), in contrast to placebo where no changes were seen; the difference in AST levels between the two groups was significant at 2 weeks (P < .02). Reduced levels of alanine transaminase (ALT) were also seen in the group consuming ACE (P < .08). Previous studies showed reduction of chronic pain when consuming 1 g ACE per day. The higher dose of 2.3 g/day in this study was associated with significant reduction of chronic pain at rest and when physically active (P < .05). Consumption of ACE showed safety regarding markers pertaining to anticoagulant activity and platelet activation status, in conjunction with rapid and robust relief of chronic pain. Reduction in AST and ALT suggested improvement in liver function and metabolism.

  13. Platelet Activation and Thrombus Formation over IgG Immune Complexes Requires Integrin αIIbβ3 and Lyn Kinase.

    Science.gov (United States)

    Zhi, Huiying; Dai, Jing; Liu, Junling; Zhu, Jieqing; Newman, Debra K; Gao, Cunji; Newman, Peter J

    2015-01-01

    IgG immune complexes contribute to the etiology and pathogenesis of numerous autoimmune disorders, including heparin-induced thrombocytopenia, systemic lupus erythematosus, rheumatoid- and collagen-induced arthritis, and chronic glomerulonephritis. Patients suffering from immune complex-related disorders are known to be susceptible to platelet-mediated thrombotic events. Though the role of the Fc receptor, FcγRIIa, in initiating platelet activation is well understood, the role of the major platelet adhesion receptor, integrin αIIbβ3, in amplifying platelet activation and mediating adhesion and aggregation downstream of encountering IgG immune complexes is poorly understood. The goal of this investigation was to gain a better understanding of the relative roles of these two receptor systems in immune complex-mediated thrombotic complications. Human platelets, and mouse platelets genetically engineered to differentially express FcγRIIa and αIIbβ3, were allowed to interact with IgG-coated surfaces under both static and flow conditions, and their ability to spread and form thrombi evaluated in the presence and absence of clinically-used fibrinogen receptor antagonists. Although binding of IgG immune complexes to FcγRIIa was sufficient for platelet adhesion and initial signal transduction events, platelet spreading and thrombus formation over IgG-coated surfaces showed an absolute requirement for αIIbβ3 and its ligands. Tyrosine kinases Lyn and Syk were found to play key roles in IgG-induced platelet activation events. Taken together, our data suggest a complex functional interplay between FcγRIIa, Lyn, and αIIbβ3 in immune complex-induced platelet activation. Future studies may be warranted to determine whether patients suffering from immune complex disorders might benefit from treatment with anti-αIIbβ3-directed therapeutics.

  14. Platelet Activation and Thrombus Formation over IgG Immune Complexes Requires Integrin αIIbβ3 and Lyn Kinase.

    Directory of Open Access Journals (Sweden)

    Huiying Zhi

    Full Text Available IgG immune complexes contribute to the etiology and pathogenesis of numerous autoimmune disorders, including heparin-induced thrombocytopenia, systemic lupus erythematosus, rheumatoid- and collagen-induced arthritis, and chronic glomerulonephritis. Patients suffering from immune complex-related disorders are known to be susceptible to platelet-mediated thrombotic events. Though the role of the Fc receptor, FcγRIIa, in initiating platelet activation is well understood, the role of the major platelet adhesion receptor, integrin αIIbβ3, in amplifying platelet activation and mediating adhesion and aggregation downstream of encountering IgG immune complexes is poorly understood. The goal of this investigation was to gain a better understanding of the relative roles of these two receptor systems in immune complex-mediated thrombotic complications. Human platelets, and mouse platelets genetically engineered to differentially express FcγRIIa and αIIbβ3, were allowed to interact with IgG-coated surfaces under both static and flow conditions, and their ability to spread and form thrombi evaluated in the presence and absence of clinically-used fibrinogen receptor antagonists. Although binding of IgG immune complexes to FcγRIIa was sufficient for platelet adhesion and initial signal transduction events, platelet spreading and thrombus formation over IgG-coated surfaces showed an absolute requirement for αIIbβ3 and its ligands. Tyrosine kinases Lyn and Syk were found to play key roles in IgG-induced platelet activation events. Taken together, our data suggest a complex functional interplay between FcγRIIa, Lyn, and αIIbβ3 in immune complex-induced platelet activation. Future studies may be warranted to determine whether patients suffering from immune complex disorders might benefit from treatment with anti-αIIbβ3-directed therapeutics.

  15. Leukaemia-associated Rho guanine nucleotide exchange factor (LARG) plays an agonist specific role in platelet function through RhoA activation.

    Science.gov (United States)

    Zou, Siying; Teixeira, Alexandra M; Yin, Mingzhu; Xiang, Yaozu; Xavier-Ferrucio, Juliana; Zhang, Ping-Xia; Hwa, John; Min, Wang; Krause, Diane S

    2016-08-30

    Leukemia-Associated RhoGEF (LARG) is highly expressed in platelets, which are essential for maintaining normal haemostasis. We studied the function of LARG in murine and human megakaryocytes and platelets with Larg knockout (KO), shRNA-mediated knockdown and small molecule-mediated inhibition. We found that LARG is important for human, but not murine, megakaryocyte maturation. Larg KO mice exhibit macrothrombocytopenia, internal bleeding in the ovaries and prolonged bleeding times. KO platelets have impaired aggregation, α-granule release and integrin α2bβ3 activation in response to thrombin and thromboxane, but not to ADP. The same agonist-specific reductions in platelet aggregation occur in human platelets treated with a LARG inhibitor. Larg KO platelets have reduced RhoA activation and myosin light chain phosphorylation, suggesting that Larg plays an agonist-specific role in platelet signal transduction. Using two different in vivo assays, Larg KO mice are protected from in vivo thrombus formation. Together, these results establish that LARG regulates human megakaryocyte maturation, and is critical for platelet function in both humans and mice.

  16. Effects of Buyang Huanwu decoction and Astragalus mongholicus on platelet activating factor receptor activity in rabbits in vitro

    Institute of Scientific and Technical Information of China (English)

    Hui Yao; Jiping Zhang; Zhixi Chen; Yongjie Wu; Zhiqiang Li

    2006-01-01

    BACKGROUND:The pharmacological action of traditional Chinese medicine compound is the comprehensive effect of the various ingredients,and the interactions of various ingredients are closely correlated with the final effect.In order to reveal the compatibility mechanism of BHD's prescription in treating and preventing ischemic cerebrovascular disease,we needed explore the effect and relation of ingredients in the prescription.OBJECTIVE:To observe the effect of Buyang Huanwu decoction(BHD)and Astragalus mongholicus on the activity of platelet activating factor receptor(PAFR)in the platelet of rabbits in vitro,and investigate the mechanism of Astragalus mongholicus.DESIGN:A decomposed recipes study.SETTING:Guangzhou University of Traditional Chinese Medicine.MATERIALS:Five New Zealand rabbits,weighing 2-3 kg,both sexes,were used.BHD was composed of Sheng Huang Qi 120 g,Dang Gui Wei 6 g,Chi Shao 4.5 g,Chuan Xiong 3 g,Di Long 3 g,Tao Ren 3 g,Hong Hua 3 g.The prescription for activating blood circulation consisted of Dang Gui Wei 6 g,Chi Shao 4.5 g,Chuan Xiong 3 g,Di Long 3 g,Tao Ren 3 g and Hong Hua 3 g.The prescription for invigorating qi consisted of 120 g Sheng Huang Qi.The prepared herbal pieces were purchased from the traditional Chinese medicine Dispensary of Foshan Second People's Hospital,and appraised by Professor Xu from Science of Chinese Materia Medica College,Guangzhou University of Traditional Chinese Medicine.3H-PAF was supplied by Amersham Co.,Ltd.(specific activity:6.475 TBq/mmol;batch number:200402);PAF standard by Biomol Co.,Ltd.(batch number:P1318V).METHODS:The experiments were carried out in the Laboratory of Nuclear Medicine,Guangzhou University of Traditional Chinese Medicine from September to December 2004.①Injections of BHD,prescriptions for activating blood circulation and invigorating qi were prepared by the decoction and alcohol sedimentation technique.Rabbit common carotid artery blood(40 mL)was drawn via intubation to prepare platelet

  17. High-dose aspirin in addition to daily low-dose aspirin decreases platelet activation in patients before and after percutaneous coronary intervention.

    Science.gov (United States)

    ten Berg, Jurriën M; Gerritsen, Wim B M; Haas, Fred J L M; Kelder, Hans C; Verheugt, Freek W A; Plokker, H W Thijs

    2002-03-01

    Activated platelets play a major role in acute vessel closure after coronary angioplasty. Although aspirin is the routine therapy during angioplasty, it only incompletely prevents acute closure. This might be due to suboptimal dosing. First, to study the effect of additional high-dose aspirin on platelet activation during coronary angioplasty. Second, to assess the potential of the new PFA-100 analyzer to evaluate the effect of different doses of aspirin in patients undergoing angioplasty. Fifty-one patients on 100 mg aspirin/day for at least 1 month were randomized to continuation of 100 mg aspirin/day only (Group A=24 patients), or to this regime plus a bolus of 1000 mg of aspirin given 1 day before angioplasty (Group B=27 patients). Results were compared with 15 controls. Platelet function was measured before angioplasty by the PFA-100 analyzer; platelet activation was measured by flow cytometry just before and 1 h after angioplasty. At baseline, Group A had significantly more activated platelets than the control group (P<.001). High-dose aspirin in Group B resulted in significantly lower platelet activation as compared with both controls (P<.001) and Group A (P<.001). During angioplasty, the number of activated platelets decreased significantly in Group A (P<.001), while there was no change in Group B (P=.6). The PFA-100 analyzer was unable to detect differences between the two treatment groups. The addition of high-dose aspirin to daily low-dose aspirin, 1 day before coronary angioplasty, significantly reduced the platelet activation state before and after intervention. The PFA-100 analyzer did not detect differences in the effect of low- versus high-dose aspirin on platelet function.

  18. New Steroidal Glycosides Isolated as CD40L Inhibitors of Activated Platelets

    Directory of Open Access Journals (Sweden)

    Haifeng Chen

    2010-06-01

    Full Text Available Three new compounds were isolated from the dried bulbs of Allium macrostemon Bunge. Their structures were elucidated from their spectral data as (25R-26-O-β-D-glucopyranosyl-5α-furostane-3β,12β,22,26-tetraol-3-O-β-D-glucopyranos-yl (1→2 [β-D-glucopyranosyl (1→3]-β-D-glucopyranosyl (1→4-β-D-galactopyranoside (1, (25R-26-O-β-D-glucopyranosyl-5α-furostane-3β,12α,22,26-tetraol-3-O-β-D-glucopyranosyl (1→2 [β-D-glucopyranosyl (1→3]-β-D-glucopyranosyl (1→4-β-D-galacto- pyranoside (2 and (25R-26-O-β-D-glucopyranosyl-5β-furostane-3β,12α,22,26-tetraol-3-O-β-D-glucopyranosyl (1→2-β-D-galactopyranoside (3, respectively. The inhibition effect of all compounds on CD40 ligand (CD40L expression on the membrane of activated platelets stimulated by ADP was tested. Compounds 1 and 2 exhibited significant inhibitory activities in a dose dependent manner (P < 0.05, suggesting their potential application as CD40L inhibitors.

  19. Increase in plasma platelet-activating factor levels in enterally fed preterm infants.

    Science.gov (United States)

    MacKendrick, W; Hill, N; Hsueh, W; Caplan, M

    1993-01-01

    Because platelet-activating factor (PAF) has been implicated in the pathogenesis of neonatal necrotizing enterocolitis (NEC), we designed a prospective study to examine plasma PAF levels during the first 14 days of feeding in a population of neonates of less than 32 weeks gestation. We found that significantly more patients had detectable plasma PAF levels on days 3 and 14 of feeding when compared to their prefeeding levels (7% on day 0 vs. 26% at day 3, p = 0.04; none on day 0 vs. 18.5% at day 14, p = 0.01). This finding could not be explained by decreased plasma activity of acetylhydrolase, the PAF breakdown enzyme, spontaneous endotoxinemia or a maturational effect. None of the infants who developed detectable PAF levels after feedings were begun went on to develop NEC. We conclude that our findings may reflect increased intestinal PAF production with the provision of feedings to some premature infants. However, this phenomenon by itself does not appear to be a sufficient condition for the subsequent development of NEC.

  20. Diabetic foot ulcer treatment by activated platelet rich plasma: a clinical study

    Directory of Open Access Journals (Sweden)

    Tung Dang-Xuan Tran

    2014-02-01

    Full Text Available Diabetic foot ulcer is a major complication of diabetes mellitus. It occurred in about 15% of all diabetic patients. To date, the outcome of management of diabetic foot ulcer is poor and low sufficient. Some new therapies were suggested to manage and treat this disease. In almost therapies, management of diabetic foot ulcer relates to debridement of the wound, revascularization, off-loading of the ulcer, antibacterial actions, stimulating granulation, epidermization and angiogenesis. This study aimed to evaluate the effects of activated platelet rich plasma (aPRP on diabetic foot ulcer healing on volunteer patients. There were 6 patients enrolled in this study. All patients have non-healing foot ulcers. aPRP was isolated from peripheral blood and activated with calcium chloride. Patients were injected with aPRP two times with 14-day interval. All patients were monitored during 12 weeks. The results showed that 100% (6/6 ulcers completely closed after about 7 weeks. This result initially suggests that aPRP injection is efficient method to treat the non-healing foot ulcers. Level of evidence: IV [Biomed Res Ther 2014; 1(2.000: 37-42

  1. Elevated Platelet Activating Factor Level in Ischemia-Related Arrhythmia and Its Electrophysiological Effect on Myocardium

    Institute of Scientific and Technical Information of China (English)

    TAO Yong Kang; ZHAO Shui Ping; YU Pu Lin; SHI Jing; GU Cheng Dong; SUN Hong Tao; ZHANG Guo Qiang

    2013-01-01

    Objective The mechanism through which platelet activating factor (PAF) induces cardiac electrical activity and arrhythmia is not well understood and previous studies have suggested a potential involvement of ion channels in its action. The present study was aimed to clarify the role of PAF in fatal arrhythmias following acute myocardia infarction (AMI) and the underlying mechanism. Methods (1) Blood PAF levels were measured among 72 AMI patients at the time of diagnosis with AMI and 48 h later, and their electrocardiogram (ECG) was recorded continuously. (2) Ischemia simulation and surface electrocardiogram were conducted in 20 pigs and their PAF levels were measured. (3) PAF perfusion and standard microelectrode recording were performed on guinea pig papillary muscles. Results In both humans and pigs, elevated PAF levels were detected in AMI and simulated ischemia, respectively, and even higher PAF levels were found when fatal arrhythmias occurred. In guinea pig myocardium, PAF induced a shortening of action potential duration at 90% level of repolarization (APD90)under non-ischemic conditions and a more pronounced shortening under early simulated ischemic conditions. Conclusion AMI and ischemia are associated with increased PAF levels in humans and pigs, which are further raised when fatal arrhythmia follows. The effects of PAF on the myocardium may be mediated by multiple ion channels.

  2. Online Social Activity Reflects Economic Status

    CERN Document Server

    Liu, Jin-Hu; Shao, Junming; Zhou, Tao

    2015-01-01

    To characterize economic development and diagnose the economic health condition, several popular indices such as gross domestic product (GDP), industrial structure and income growth are widely applied. However, computing these indices based on traditional economic census is usually costly and resources consuming, and more importantly, following a long time delay. In this paper, we analyzed nearly 200 million users' activities for four consecutive years in the largest social network (Sina Microblog) in China, aiming at exploring latent relationships between the online social activities and local economic status. Results indicate that online social activity has a strong correlation with local economic development and industrial structure, and more interestingly, allows revealing the macro-economic structure instantaneously with nearly no cost. Beyond, this work also provides a new venue to identify risky signal in local economic structure.

  3. Online social activity reflects economic status

    Science.gov (United States)

    Liu, Jin-Hu; Wang, Jun; Shao, Junming; Zhou, Tao

    2016-09-01

    To characterize economic development and diagnose the economic health condition, several popular indices such as gross domestic product (GDP), industrial structure and income growth are widely applied. However, computing these indices based on traditional economic census is usually costly and resources consuming, and more importantly, following a long time delay. In this paper, we analyzed nearly 200 million users' activities for four consecutive years in the largest social network (Sina Microblog) in China, aiming at exploring latent relationships between the online social activities and local economic status. Results indicate that online social activity has a strong correlation with local economic development and industrial structure, and more interestingly, allows revealing the macro-economic structure instantaneously with nearly no cost. Beyond, this work also provides a new venue to identify risky signal in local economic structure.

  4. Lack of platelet monoamine oxidase activity in Cebus monkeys (Cebus albifrons).

    Science.gov (United States)

    Heintz, R; Richardson, M A; Perumal, A S; Casey, D E

    1989-01-01

    1. Recent evidence suggests that monoamine oxidase (MAO) plays an important role modulating the extrapyramidal syndromes produced by neuroleptic drugs in both human and nonhuman primates. 2. To evaluate the possibility of using peripheral blood platelet MAO-B levels as indices of central nervous system MAO-B effects, we measured platelet MAO-B levels in Cebus monkeys that were previously tested with neuroleptics (N = 36) or drug naive (N = 6). 3. No platelet MAO-B was consistently detectable in these blood samples. 4. Thus platelet measures of MAO-B do not reliably reflect brain MAO-B function in nonhuman primates and do not offer a useful model for studying blood-brain MAO-B relationships.

  5. Antimicrobial activity of pure platelet-rich plasma against microorganisms isolated from oral cavity

    National Research Council Canada - National Science Library

    Drago, Lorenzo; Bortolin, Monica; Vassena, Christian; Taschieri, Silvio; Del Fabbro, Massimo

    2013-01-01

    .... In this study, the antimicrobial effect of pure platelet-rich plasma (P-PRP) was evaluated against oral cavity microorganisms such as Enterococcus faecalis, Candida albicans, Streptococcus agalactiae, Streptococcus oralis and Pseudomonas aeruginosa...

  6. Investigation of platelet function and platelet disorders using flow cytometry.

    Science.gov (United States)

    Rubak, Peter; Nissen, Peter H; Kristensen, Steen D; Hvas, Anne-Mette

    2016-01-01

    Patients with thrombocytopenia or platelet disorders are at risk of severe bleeding. We report the development and validation of flow cytometry assays to diagnose platelet disorders and to assess platelet function independently of platelet count. The assays were developed to measure glycoprotein levels (panel 1) and platelet function (panel 2) in sodium citrated blood. Twenty healthy volunteers and five patients diagnosed with different platelet disorders were included. Glycoprotein expression levels of the receptors Ia, Ib, IIb, IIIa and IX were measured and normalised with forward scatter (FS) as a measurement of platelet size. Platelet function was assessed by CD63, P-selectin and bound fibrinogen in response to arachidonic acid, adenosine diphosphate (ADP), collagen-related peptide, ristocetin and thrombin receptor-activation peptide-6. All patients except one with suspected δ-granule defect showed aberrant levels of glycoproteins in panel 1. Glanzmann's thrombasthenia and genetically verified Bernard-Soulier syndrome could be diagnosed using panel 1. All patients showed reduced platelet function according to at least one agonist. Using panel 2 it was possible to diagnose Bernard-Soulier syndrome, δ-granule defect and GPVI disorder. By combining the two assays, we were able to diagnose different platelet disorders and investigate platelet function independent of platelet count.

  7. Lactobacillus acidophilus alleviates platelet-activating factor-induced inflammatory responses in human intestinal epithelial cells.

    Directory of Open Access Journals (Sweden)

    Alip Borthakur

    Full Text Available Probiotics have been used as alternative prevention and therapy modalities in intestinal inflammatory disorders including inflammatory bowel diseases (IBD and necrotizing enterocolitis (NEC. Pathophysiology of IBD and NEC includes the production of diverse lipid mediators, including platelet-activating factor (PAF that mediate inflammatory responses in the disease. PAF is known to activate NF-κB, however, the mechanisms of PAF-induced inflammation are not fully defined. We have recently described a novel PAF-triggered pathway of NF-κB activation and IL-8 production in intestinal epithelial cells (IECs, requiring the pivotal role of the adaptor protein Bcl10 and its interactions with CARMA3 and MALT1. The current studies examined the potential role of the probiotic Lactobacillus acidophilus in reversing the PAF-induced, Bcl10-dependent NF-κB activation and IL-8 production in IECs. PAF treatment (5 µM×24 h of NCM460 and Caco-2 cells significantly increased nuclear p65 NF-κB levels and IL-8 secretion (2-3-fold, P<0.05, compared to control, which were blocked by pretreatment of the cells for 6 h with L. acidophilus (LA or its culture supernatant (CS, followed by continued treatments with PAF for 24 h. LA-CS also attenuated PAF-induced increase in Bcl10 mRNA and protein levels and Bcl10 promoter activity. LA-CS did not alter PAF-induced interaction of Bcl10 with CARMA3, but attenuated Bcl10 interaction with MALT1 and also PAF-induced ubiquitination of IKKγ. Efficacy of bacteria-free CS of LA in counteracting PAF-induced inflammatory cascade suggests that soluble factor(s in the CS of LA mediate these effects. These results define a novel mechanism by which probiotics counteract PAF-induced inflammation in IECs.

  8. Platelets and infection — an emerging role of platelets in viral infection

    Directory of Open Access Journals (Sweden)

    Alice eAssinger

    2014-12-01

    Full Text Available Platelets are anucleate blood cells that play a crucial role in the maintenance of hemostasis. While platelet activation and elevated platelet counts (thrombocytosis are associated with increased risk of thrombotic complications, low platelet counts (thrombocytopenia and several platelet function disorders increase the risk of bleeding. Over the last years more and more evidence has emerged that platelets and their activation state can also modulate innate and adaptive immune responses and low platelet counts have been identified as a surrogate marker for poor prognosis in septic patients.Viral infections often coincide with platelet activation. Host inflammatory responses result in the release of platelet activating mediators and a pro-oxidative and pro-coagulant environment, which favours platelet activation. However, viruses can also directly interact with platelets and megakaryocytes and modulate their function. Furthermore, platelets can be activated by viral antigen-antibody complexes and in response to some viruses B-lymphocytes also generate anti-platelet antibodies.All these processes contributing to platelet activation result in increased platelet consumption and removal and often lead to thrombocytopenia, which is frequently observed during viral infection. However, virus-induced platelet activation does not only modulate platelet count, but also shapes immune responses. Platelets and their released products have been reported to directly and indirectly suppress infection and to support virus persistence in response to certain viruses, making platelets a double-edged sword during viral infections. This review aims to summarize the current knowledge on platelet interaction with different types of viruses, the viral impact on platelet activation and platelet-mediated modulations of innate and adaptive immune responses.

  9. Platelets and infection - an emerging role of platelets in viral infection.

    Science.gov (United States)

    Assinger, Alice

    2014-01-01

    Platelets are anucleate blood cells that play a crucial role in the maintenance of hemostasis. While platelet activation and elevated platelet counts (thrombocytosis) are associated with increased risk of thrombotic complications, low platelet counts (thrombocytopenia) and several platelet function disorders increase the risk of bleeding. Over the last years, more and more evidence has emerged that platelets and their activation state can also modulate innate and adaptive immune responses and low platelet counts have been identified as a surrogate marker for poor prognosis in septic patients. Viral infections often coincide with platelet activation. Host inflammatory responses result in the release of platelet activating mediators and a pro-oxidative and pro-coagulant environment, which favors platelet activation. However, viruses can also directly interact with platelets and megakaryocytes and modulate their function. Furthermore, platelets can be activated by viral antigen-antibody complexes and in response to some viruses B-lymphocytes also generate anti-platelet antibodies. All these processes contributing to platelet activation result in increased platelet consumption and removal and often lead to thrombocytopenia, which is frequently observed during viral infection. However, virus-induced platelet activation does not only modulate platelet count but also shape immune responses. Platelets and their released products have been reported to directly and indirectly suppress infection and to support virus persistence in response to certain viruses, making platelets a double-edged sword during viral infections. This review aims to summarize the current knowledge on platelet interaction with different types of viruses, the viral impact on platelet activation, and platelet-mediated modulations of innate and adaptive immune responses.

  10. Collagen-stimulated activation of Syk but not c-Src is severely compromised in human platelets lacking membrane glycoprotein VI.

    Science.gov (United States)

    Ichinohe, T; Takayama, H; Ezumi, Y; Arai, M; Yamamoto, N; Takahashi, H; Okuma, M

    1997-01-03

    Activation of circulating platelets by subendothelial collagen is an essential event in vascular hemostasis. In human platelets, two membrane glycoprotein (GP) abnormalities, integrin alpha2 beta1 deficiency and GPVI deficiency, have been reported to result in severe hyporesponsiveness to fibrillar collagen. Although it has been well established that integrin alpha2 beta1, also known as the GPIa-IIa complex, functions as a primary platelet adhesion receptor for collagen, the mechanism by which GPVI contributes to collagen-platelet interaction has been ill defined to date. However, our recent observation that GPVI cross-linking couples to cyclic AMP-insensitive activation of c-Src and Syk tyrosine kinases suggested a potential role for GPVI in regulating protein-tyrosine phosphorylation by collagen (Ichinohe, T., Takayama, H., Ezumi, Y., Yanagi, S., Yamamura, H., and Okuma, M. (1995) J. Biol. Chem. 270, 28029-28036). To further investigate this hypothesis, here we examined the collagen-induced protein-tyrosine phosphorylation in GPVI-deficient platelets expressing normal amounts of alpha2 beta1. In response to collagen, these platelets exhibited alpha2 beta1-dependent c-Src activation accompanied by tyrosine phosphorylation of several substrates including cortactin. In contrast, severe defects were observed in collagen-stimulated Syk activation and tyrosine phosphorylation of phospholipase C-gamma2, Vav, and focal adhesion kinase, implicating a specific requirement of GPVI for recruiting these molecules to signaling cascades evoked by collagen-platelet interaction.

  11. Elevated thrombopoietin and platelet indices confirm active thrombopoiesis but fail to predict clinical severity of puumala hantavirus infection

    Science.gov (United States)

    Laine, Outi; Joutsi-Korhonen, Lotta; Lassila, Riitta; Huhtala, Heini; Vaheri, Antti; Mäkelä, Satu; Mustonen, Jukka

    2016-01-01

    Abstract We evaluated the mechanisms of thrombocytopenia and procoagulant changes in relation with clinical variables in a cohort of patients with acute hantavirus disease. Blood samples of 33 prospectively recruited, consecutive, hospitalized patients with acute Puumala virus–induced hemorrhagic fever with renal syndrome (HFRS) were collected acutely and at the recovery visit (control). Serum thrombopoietin (TPO) and activity of plasma microparticles (MPs) from various cell sources were measured with enzyme-linked immunosorbent assay-based methods. The results were related to data on platelet indices and functions, coagulation variables, and clinical disease. Serum TPO was nearly 4-fold higher acutely compared with the control (median 207 pg/mL, range 56–1258 pg/mL vs. median 58 pg/mL, range 11–241 pg/mL, P < 0.001) and coincided with high mean platelet volume (MPV) and immature platelet fraction (IPF%). Prothrombin fragments and D-dimer were high acutely compared with the control (F1 + 2 median 704 pmol/L, range 284–1875 pmol/L vs. median 249 pmol/L, range 118–556 pmol/L, P < 0.001; d-dimer median 2.8 mg/L, range 0.6–34.0 mg/L vs. median 0.4 mg/L, range 0.2–1.1 mg/L, P < 0.001), and associated with low platelet count and severe acute kidney injury (AKI). MPs’ procoagulant activity was high acutely only among patients with mild AKI (plasma creatinine below the median at the time of the measurement). Upregulated TPO together with high MPV and IPF% confirm active thrombopoiesis, but do not predict severity of HFRS. Simultaneously, elevated prothrombin fragments and d-dimer suggest increased consumption of platelets in patients with severe AKI. Activity of platelet-derived MPs in HFRS should be studied with flow cytometry in a larger cohort of patients. PMID:28033261

  12. Alkali treatment of microrough titanium surfaces affects macrophage/monocyte adhesion, platelet activation and architecture of blood clot formation

    Directory of Open Access Journals (Sweden)

    V Milleret

    2011-05-01

    Full Text Available Titanium implants are most commonly used for bone augmentation and replacement due to their favorable osseointegration properties. Here, hyperhydrophilic sand-blasted and acid-etched (SBA titanium surfaces were produced by alkali treatment and their responses to partially heparinized whole human blood were analyzed. Blood clot formation, platelet activation and activation of the complement system was analyzed revealing that exposure time between blood and the material surface is crucial as increasing exposure time results in higher amount of activated platelets, more blood clots formed and stronger complement activation. In contrast, the number of macrophages/monocytes found on alkali-treated surfaces was significantly reduced as compared to untreated SBA Ti surfaces. Interestingly, when comparing untreated to modified SBA Ti surfaces very different blood clots formed on their surfaces. On untreated Ti surfaces blood clots remain thin (below 15 mm, patchy and non-structured lacking large fibrin fiber networks whereas blood clots on differentiated surfaces assemble in an organized and layered architecture of more than 30 mm thickness. Close to the material surface most nucleated cells adhere, above large amounts of non-nucleated platelets remain entrapped within a dense fibrin fiber network providing a continuous cover of the entire surface. These findings might indicate that, combined with findings of previous in vivo studies demonstrating that alkali-treated SBA Ti surfaces perform better in terms of osseointegration, a continuous and structured layer of blood components on the blood-facing surface supports later tissue integration of an endosseous implant.

  13. In vitro effects of vitamin supplements on platelet-activating factor and its metabolism in age-related macular degeneration.

    Science.gov (United States)

    Moschos, Marilita M; Chatziralli, Irini P; Stamatakis, George; Papakonstantinou, Vasiliki D; Demopoulos, Constantinos A

    2014-09-01

    The purpose of our study was to investigate for the first time a series of vitamin supplements used for age-related macular degeneration (AMD) as potential inhibitors of platelet-activating factor (PAF). Various vitamin supplements were tested in washed rabbit platelets (WRPs), in order to investigate the interaction between vitamin supplements (InShape, Nutrof, Ocuvite, Vitalux) and inhibition of PAF-induced platelet aggregation. Additionally, we examined their ability to affect PAF-metabolism, through their in vitro effect on PAF basic metabolic enzymes (PAF-CPT, lyso PAF-AT, and PAF-AH). Nutrof exhibited the strongest anti-PAF activity, while Vitalux was the most potent anti-inflammatory factor. This is the first study to bring in surface potent anti-inflammatory and anti-angiogenic activities of some vitamin supplements used against AMD, through their in vitro anti-PAF effects in WRPs and the rabbit plasma and leukocyte PAF metabolism, suggesting a promising role of vitamin supplements and especially resveratrol, concerning its potent anti-angiogenic activity in AMD.

  14. Can the mean platelet volume be a predictor of disease activity in primary Sjogren syndrome?

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    Ahmet Omma

    2016-04-01

    Full Text Available Background: Disease activity in primary Sjogren syndrome (PSS is measured by the EULAR Sjogren's syndrome disease activity index (ESSDAI and patient reported index (ESSPRI. Studies investigating the association between ESSDAI and ESSPRI and previously reported indicators of systemic inflammation are few in the literature. The aim of this study was to determine the clinical utility of the mean platelet volume (MPV in predicting disease activity in PSS patients. Methods: A total of 190 subjects including ninety-five PSS patients and ninety-five healthy controls were enrolled. Associations between MPV and other known indicators of systemic inflammation (red cell distribution width (RDW, neutrophil to lymphocyte ratio (NLR and patient clinical characteristic, ESSDAI and ESSPRI were investigated by using spearman correlation and linear regression analysis. Results: MPV levels were found to be significantly higher in the PSS group than the control group (10.5+/-1.2 versus 9.0+/-1; P<0.001 respectively. Correlation and regression analysis showed a positive correlation between MPV levels and ESSDAI scores (r=0.24, p=0.01. There was a negative correlation between ESSPRI and MPV levels (r=-0.32, p=0.001. NLR and RDW did not show any significant correlation with either ESSDAI or ESSPRI scores. Conclusions: MPV levels are significantly elevated in PSS patients compared to their control peers, positively correlate with ESSDAI but negatively with ESSPRI scores. MPV might be a useful inflammatory marker to measure disease activity in PSS. [Int J Res Med Sci 2016; 4(4.000: 1237-1241

  15. In vitro effect of anti-β2 glycoprotein I antibodies on P-selectin expression, a marker of platelet activation

    Directory of Open Access Journals (Sweden)

    A. Hoxha

    2012-03-01

    Full Text Available Antiphospholipid antibodies (aPL associated with thromboembolic events and/or pregnancy morbidity characterize the so-called antiphospholipid syndrome (APS. Beta2glycoprotein I (β2GPI is the main target antigen for aPL, but the pathogenic role of anti-β2GPI antibodies (aβ2GPI is still unclear. Some authors assume they play a role in activating platelets. We evaluated the effects of aβ2GPI antibodies on platelet P-selectin expression. Aβ2GPI antibodies in the plasma of a pregnant APS patient were isolated by affinity chromatography at two different stages (catastrophic and quiescent of the disease. Gel filtered platelets (100 x 109/L from healthy volunteers were incubated with β2-GPI (20 µg/mL and with different concentrations (5. 25 and 50 µg/mL of aβ2GPI antibodies. P-selectin surface expression on platelets was assessed by flow cytometry using a specific fluorescent antibody directed against P-selectin. Aβ2GPI antibodies induced platelet activation only in the presence of thrombin receptor activator for peptide 6 (TRAP-6, a platelet agonist, at a subthreshold concentration. Aβ2GPI antibody enhancement on platelet surface P-selectin expression was stronger in the catastrophic than in the quiescent phase of the disease (47 vs 15%. TRAP-6 dependent platelet activation by aβ2GPI antibodies is consistent with the “two hit” pathogenetic hypothesis for thrombosis. Aβ2GPI antibodies induce higher platelet P-selectin expression during the active rather than the acute phases.

  16. Platelet-induced thrombin generation by the calibrated automated thrombogram assay is increased in patients with essential thrombocythemia and polycythemia vera.

    Science.gov (United States)

    Panova-Noeva, Marina; Marchetti, Marina; Spronk, Henri Maria; Russo, Laura; Diani, Erika; Finazzi, Guido; Finazzi, Good; Salmoiraghi, Silvia; Rambaldi, Alessandro; Rambaldi, Aueesandrd; Barbui, Tiziano; Barbui, Titiano; Ten Cate, Hugo; Ten Cate, Huao; Falanga, Anna

    2011-04-01

    The platelet contribution to the thrombophilic state of patients with myeloproliferative neoplasms (MPNs), i.e., essential thrombocythemia (ET) and polycythemia vera (PV), remains uncertain. In this study we aimed to characterize the thrombin generation (TG) potential expressed by platelets from these subjects, compare it to normal platelets, and identify what factors might be responsible for platelet TG. In a group of 140 MPN patients (80 ET and 60 PV) and 72 healthy subjects, we measured the global procoagulant potential of platelet-rich plasma (PRP) utilizing the TG assay by the calibrated automated thrombogram (CAT). To characterize the procoagulant contribution of platelets in PRP, the TG of both isolated platelets and platelet-poor plasma was measured, and the platelet surface expression of TF was determined. Finally, the activation status of platelets was assessed by the levels of P-selectin expressed on platelet surface. MPN patients had significantly increased PRP and isolated platelet TG potential compared to controls. This was associated to the occurrence of platelet activation. Patients carriers of the JAK2V617F mutation showed the highest values of TG and platelet surface TF and P-selectin. Platelet TG potential was significantly lower in hydroxyurea(HU) compared to non-HU-treated patients and was lowest in HU-treated JAK2V617F carriers. In subjects not receiving HU, platelet TG significantly increased by JAK2V617F allele burden increment (P < 0.05).This study demonstrates a platelet-dependent form of hypercoagulability in MPN patients, particularly in those carriers of the JAK2V617F mutation. The cytoreductive therapy with HU significantly affects this prothrombotic phenotype.

  17. Zinc acexamate reduces gastric damage induced by platelet-activating factor.

    Science.gov (United States)

    Escolar, G; Navarro, C; Galmés, J L; Casanovas, L I; Bulbena, O

    1989-10-01

    We have tested the ability of zinc acexamate (ZAC) to prevent platelet-activating-factor (Paf) induced gastric damage in rats. Lesions were characterized by a vascular congestion affecting the entire mucosa, oedema, haemorrhage and frequent necrosis of the more superficial areas. The gastric damage appearing after Paf was accompanied by degranulation of gastric mast cells. Leukocytes were often seen at the submucosal level. Oral pretreatment with ZAC reduced in a dose-dependent manner both gastric damage and mast cell degranulation observed after Paf. ZAC administered orally at a dose of 100 mg kg-1 statistically inhibited (p less than 0.01) gastric damage and mast cell degranulation. ZAC did not affect the hypotension induced by Paf confirming that gastric damage and hypotension appearing in rats after Paf administration are two independent phenomena. The present findings indicate that the inhibitory effect of ZAC upon gastric lesions induced by Paf may be related to the different protective actions exhibited by this zinc compound in a wide variety of experimental models of gastric ulcer.

  18. Activation of 5-HT7 receptors increases neuronal platelet-derived growth factor β receptor expression.

    Science.gov (United States)

    Vasefi, Maryam S; Kruk, Jeff S; Liu, Hui; Heikkila, John J; Beazely, Michael A

    2012-03-09

    Several antipsychotics have a high affinity for 5-HT7 receptors yet despite intense interest in the 5-HT7 receptor as a potential drug target to treat psychosis, the function and signaling properties of 5-HT7 receptors in neurons remain largely uncharacterized. In primary mouse hippocampal and cortical neurons, as well as in the SH-SY5Y cell line, incubation with 5-HT, 5-carboxamidotryptamine (5-CT), or 5-HT7 receptor-selective agonists increases the expression of platelet-derived growth factor (PDGF)β receptors. The increased PDGFβ receptor expression is cyclic AMP-dependent protein kinase (PKA)-dependent, suggesting that 5-HT7 receptors couple to Gα(s) in primary neurons. Interestingly, up-regulated PDGFβ receptors display an increased basal phosphorylation state at the phospholipase Cγ-activating tyrosine 1021. This novel linkage between the 5-HT7 receptor and the PDGF system may be an important GPCR-neurotrophic factor signaling pathway in neurons.

  19. Endogenous bacterial toxins are required for the injurious action of platelet-activating factor in rats.

    Science.gov (United States)

    Sun, X M; MacKendrick, W; Tien, J; Huang, W; Caplan, M S; Hsueh, W

    1995-07-01

    Platelet-activating factor (PAF), an endogenous mediator for experimental sepsis, has been shown to induce shock and intestinal necrosis in vivo. However, it is unclear whether PAF exerts its injurious effects on the intestinal tissue directly or via synergism with other endogenous products. The aim of this study was to examine the role of endogenous bacterial products, such as endotoxin, in PAF-induced intestinal injury. PAF (3 micrograms/kg) was injected intravenously into normally colonized rats, germfree rats, and normal rats pretreated with a combination of antibiotics, and the systemic response and intestinal injury were assessed. PAF did not cause prolonged shock, leukopenia, hemoconcentration, and bowel necrosis in germfree rats. When germfree rats were primed with a low dose (0.5 mg/kg) of endotoxin, the protection was lost. Combined treatment of the normally colonized rats with neomycin, polymyxin B, and metronidazole for 7 days largely protected the animal from PAF-induced shock and intestinal necrosis. PAF does not directly induce prolonged hypotension, hemoconcentration, persistent leukopenia, and gross intestinal necrosis but causes these changes via a synergism with endogenous bacterial toxins, presumably from the gut flora.

  20. Effects of calcium-modified titanium implant surfaces on platelet activation, clot formation, and osseointegration.

    Science.gov (United States)

    Anitua, Eduardo; Prado, Roberto; Orive, Gorka; Tejero, Ricardo

    2015-03-01

    The clinical success of load bearing dental and orthopedic implants relies on adequate osseointegration. Because of its favorable properties, titanium is generally considered as the material of choice. Following implant placement, titanium surfaces establish an ionic equilibrium with the surrounding tissues in which calcium plays major roles. Calcium is a cofactor of the coagulation cascade that mediates plasma protein adsorption and intervenes in a number of other intra and extracellular processes relevant for bone regeneration. In this study, titanium surfaces were modified with calcium ions (Ca(2+) surfaces) and their responses to in vitro and in vivo models were analyzed. Unlike unmodified surfaces, Ca(2+) surfaces were superhydrophilic and induced surface clot formation, platelet adsorption and activation when exposed to blood plasma. Interestingly, in vivo osseointegration using a peri-implant gap model in rabbit demonstrated that Ca(2+) surfaces significantly improved peri-implant bone volume and density at 2 weeks and bone implant contact at 8 weeks as compared to the unmodified controls. The combination of Ca(2+) surfaces with plasma rich in growth factors produced significantly more bone contact already at 2 weeks of implantation. These findings suggest the importance of the provisional matrix formation on tissue integration and highlight the clinical potential of Ca(2+) titanium surfaces as efficient stimulators of implant osseointegration.

  1. Human platelet lysate versus minoxidil stimulates hair growth by activating anagen promoting signaling pathways.

    Science.gov (United States)

    Dastan, Maryam; Najafzadeh, Nowruz; Abedelahi, Ali; Sarvi, Mohammadreza; Niapour, Ali

    2016-12-01

    Minoxidil and human platelet lysate (HPL) are commonly used to treat patients with hair loss. However, the roles of HPL versus minoxidil in hair follicle biology largely remain unknown. Here, we hypothesized that bulge and dermal papilla (DP) cells may express specific genes, including Kras, Erk, Akt, Shh and β-catenin after exposure to minoxidil or HPL. The mouse hair follicles were isolated on day 10 after depilation and bulge or DP regions were dissected. The bulge and DP cells were cultured for 14days in DMEM/F12 medium. Then, the cells were treated with 100μM minoxidil and 10% HPL for 10 days. Nuclear morphology was identified using DAPi staining. Reverse transcriptase and real-time polymerase chain reaction (PCR) analysis were also performed to examine the expression of Kras, Erk, Akt, Shh and β-catenin mRNA levels in the treated bulge and DP regions after organ culture. Here, we found that minoxidil influences bulge and DP cell survival (Pminoxidil treatment in both bulge and DP cells. HPL mediated Erk upregulation in both bulge and DP cells (Pminoxidil-treated bulge cells. In contrast, the expression of β-cateinin and Shh in the DP cells was not meaningfully increased after treatment with HPL. Our results suggest that minoxidil and HPL can promote hair growth by activating the main anagen inducing signaling pathways. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

  2. Levels of gingival tissue platelet activating factor after conventional and regenerative periodontal surgery.

    Science.gov (United States)

    Keles, Gonca Cayir; Cetinkaya, Burcu Ozkan; Ayas, Bulent; Isildak, Ibrahim; Diraman, Emine; Koprulu, Hulya; Acikgoz, Gokhan

    2007-12-01

    The hypothesis, a relationship between gingival tissue platelet activating factor (PAF) levels and healing after periodontal surgery, was tested by measuring PAF levels in gingival tissues collected from sites that had undergone flap surgery and guided tissue regeneration (GTR) or flap surgery alone. Using a split-mouth design, 20 intrabony defects were randomly assigned to treatment with flap surgery and GTR (group 1) or with flap surgery alone (group 2). Gingival tissue samples were obtained at surgery (baseline) and at 6-month follow-up evaluation visit. One half of each sample was used for analysis of PAF levels by high-performance liquid chromatography, and the other half of the sample was used for histomorphometric analysis that included measurements of number and diameter of blood vessels. PAF levels and diameter of blood vessels were significantly decreased (p 0.05). Based on the reported results, it is suggested that a decrease in gingival PAF levels might be found after conventional and regenerative periodontal surgery.

  3. 粉防己碱对兔血小板聚集和血小板活化因子生成的影响%Effects of tetrandrine on rabbit platelet aggregation and platelet activating factor generation

    Institute of Scientific and Technical Information of China (English)

    张敏; 张乐之; 吕金胜

    1995-01-01

    目的:探讨粉防己碱(Tet)对兔血小板聚集和PAF生成的影响.方法:卡西霉素(Cal)和PAF诱导血小板聚集的聚集率和Tet对血小板聚集的抑制率被测定;给予或未给予Tet处理之血小板用Cal刺激释放PAF的量也被测定.结果:在4-64 μmol·L-1浓度范围,Tet明显抑制Cal和PAF诱导的血小板聚集.IC50值分别为8.6μmol·L-1和14.0μmol·L-1.Tet 也浓度依赖性的抑制Cal诱导血小板释放PAF,IC50值为21.0 μmol·L-1.结论:Tet抑制血小板聚集作用与抑制内源性PAF生成有关.%AIM: To study the effects of tetrandrine (Tet) on platelet aggregation and platelet activating factor (PAF) generation in rabbit platelet-rich plasma (PRP). METHODS:The aggregation rate of platelets induced by calcimycin (Cal) and PAF and the inhibition rate of Tet on platelet aggregation were measured. The amount of PAF in PRP stimulated with Cal and treated with Tet was also meaaggregation. At the final concentrations of 4PRP aggregation by Cal, there was a marked increase in PAF content. Tet dependented the release of PAF from platelets by Cal in a concentration-dependent manner, with IC50 of 21hibition effect of Tet on platelet aggregation might be concerned with the reduction of endogenous PAF generation.

  4. Skepinone-L, a Novel Potent and Highly Selective Inhibitor of p38 MAP Kinase, Effectively Impairs Platelet Activation and Thrombus Formation

    Directory of Open Access Journals (Sweden)

    Oliver Borst

    2013-06-01

    Full Text Available Background/Aims: Platelets are critically important for primary haemostasis and the major players in thrombotic vascular occlusion. Platelets are activated by agonists, such as thrombin and collagen-related peptide as well as second-wave mediators including thromboxane A2 via different intracellular signaling pathways resulting in degranulation, aggregation and thrombus formation. Platelet activation is paralleled by phosphorylation and activation of p38 MAPK. The limited specificity of hitherto known p38 MAPK inhibitors precluded safe conclusions on the precise role of p38 MAPK in the regulation of platelet function. The present study examined the impact of Skepinone-L, a novel and highly selective inhibitor of p38 mitogen-activated protein kinase (p38 MAPK, on platelet activation and thrombus formation. Methods: Experiments were performed in freshly isolated human platelets. Protein phosphorylation was quantified by Western blotting, thromboxane B2 synthesis by enzyme immunoassay, ATP release by ChronoLume luciferin assay, cytosolic Ca2+ concentration by Fura-2 fluorescence-measurements, platelet aggregation by a light transmissions measurement and in vitro thrombus formation by a flow chamber. Results: Skepinone-L (1 μM virtually abrogated the phosphorylation of platelet p38 MAPK substrate Hsp27 following stimulation with CRP (1 μg/ml, thrombin (5 mU/ml or thromboxane A2 analogue U-46619 (1 μM. Furthermore, Skepinone-L significantly blunted activation-dependent platelet secretion and aggregation following threshold concentrations of CRP, thrombin and thromboxane A2 analogue U-46619. Skepinone-L did not impair platelet Ca2+ signaling but prevented agonist-induced thromboxane A2 synthesis through abrogation of p38 MAPK-dependent phosphorylation of platelet cytosolic phospholipase A2 (cPLA2. Skepinone-L further markedly blunted thrombus formation under low (500-s and high (1700-s arterial shear rates. Conclusions: The present study discloses

  5. Activation of platelet-activating factor receptor in SZ95 sebocytes results in inflammatory cytokine and prostaglandin E2 production.

    Science.gov (United States)

    Zhang, Qiwei; Seltmann, Holger; Zouboulis, Christos C; Travers, Jeffrey B

    2006-10-01

    Platelet-activating factor (PAF) is a group of phosphocholines with various biological effects mediated by the PAF receptor (PAF-R). Activation of the epidermal PAF-R induces the expression of inflammatory mediators, including cyclooxygenase-2 (COX-2) and prostaglandin E(2) (PGE(2)). The upregulation of COX-2 expression has been shown to be involved in sebocyte proliferation, sebaceous gland inflammation and carcinogenesis. The present study was designed to investigate whether PAF-R activation could induce the expression of COX-2 and production of PGE(2), as well as secretion of the inflammatory cytokine, interleukin-8 (IL-8), in the immortalized sebaceous gland cell line SZ95. Using calcium mobilization studies, we first confirmed that PAF can signal through PAF-R in SZ95 sebocytes. We then found that the production of IL-8 was induced following treatment with PAF-R agonist, however blocked by a specific PAF-R antagonist. Induction of COX-2 expression and increased PGE(2) production were observed in SZ95 sebocytes after PAF-R activation. Finally, it was demonstrated that the production of PGE(2), induced by PAF-R activation and mediated by COX-2 expression, was blocked following PAF-R antagonism in SZ95 sebocytes. These studies suggest that SZ95 sebocytes express functional PAF-Rs and PAF-Rs are involved in regulating the expression of inflammatory mediators, including COX-2, PGE(2) and IL-8.

  6. Estrogen, inflammation, and platelet phenotype.

    Science.gov (United States)

    Miller, Virginia M; Jayachandran, Muthuvel; Hashimoto, Kazumori; Heit, John A; Owen, Whyte G

    2008-01-01

    Although exogenous estrogenic therapies increase the risk of thrombosis, the effects of estrogen on formed elements of blood are uncertain. This article examines the genomic and nongenomic actions of estrogen on platelet phenotype that may contribute to increased thrombotic risk. To determine aggregation, secretion, protein expression, and thrombin generation, platelets were collected from experimental animals of varying hormonal status and from women enrolled in the Kronos Early Estrogen Prevention Study. Estrogen receptor beta predominates in circulating platelets. Estrogenic treatment in ovariectomized animals decreased platelet aggregation and adenosine triphosphate (ATP) secretion. However, acute exposure to 17beta-estradiol did not reverse decreases in platelet ATP secretion invoked by lipopolysaccharide. Thrombin generation was positively correlated to the number of circulating microvesicles expressing phosphatidylserine. Assessing the effect of estrogen treatments on blood platelets may lead to new ways of identifying women at risk for adverse thrombotic events with such therapies.

  7. Homoerydictyl-7-O-β-D-glycosidc—A Receptor Antagonist of Platelet-activating Factor (PAF)

    Institute of Scientific and Technical Information of China (English)

    GuanZengwei; WangYinye; YangXiuwei; CuiYuxin

    2001-01-01

    Homoeriodictyl-7-O-β-D-glycoside, a flavonoid compound isolated from the Chinese medic inalherb, viscum coloratura inhibited platelet aggregation induced by platelet-activating factor(PAF), but it had no inhibitory activity on adenosine diphosphate-induced platelet aggregation. In the present study, we intended to get an insight into the mechanism of its anti-PAF action. Using [3H]PAF receptor binding assay we found that the compound exhibited inhibitory activity. The inhibitory rate was 18.5%, 28.4%, 58.7%, 78% and 78%, respestively, at concentrations of 10-8, 10-7, 10-6, 10-5 and 10-4 mol.L-1, There was a visible dose-effect relationship as well as a correlation between different concentrations and their inhibitory rates (r=0.985, P<0.05) when the dose was equal to or less than 1×10-5 mol.L-1, and its IC50 was 8.0×10-7 mol.L-1. The inhibitory rate didn't increase with increasing concentration of the compound when it went beyond1×10-5 mol.L-1 indicating competitive inhibition of binding of [3H]PAF to PAF receptor reached saturation.

  8. A critical role for the transient receptor potential channel type 6 in human platelet activation.

    Directory of Open Access Journals (Sweden)

    Hari Priya Vemana

    Full Text Available While calcium signaling is known to play vital roles in platelet function, the mechanisms underlying its receptor-operated calcium entry component (ROCE remain poorly understood. It has been proposed, but never proven in platelets, that the canonical transient receptor potential channel-6 (TRPC6 mediates ROCE. Nonetheless, we have previously shown that the mouse TRPC6 regulates hemostasis, thrombogenesis by regulating platelet aggregation. In the present studies, we used a pharmacological approach to characterize the role of TRPC6 in human platelet biology. Thus, interestingly, we observed that a TRPC6 inhibitor exerted significant inhibitory effects on human platelet aggregation in a thromboxane receptor (TPR-selective manner; no additional inhibition was observed in the presence of the calcium chelator BAPTA. This inhibitor also significantly inhibited human platelet secretion (dense and alpha granules, integrin IIb-IIIa, Akt and ERK phosphorylation, again, in a TPR-selective manner; no effects were observed in response to ADP receptor stimulation. Furthermore, there was a causal relationship between these inhibitory effects, and the capacity of the TRPC6 inhibitor to abrogate elevation in intracellular calcium, that was again found to be TPR-specific. This effect was not found to be due to antagonism of TPR, as the TRPC6 inhibitor did not displace the radiolabeled antagonist [3H]SQ29,548 from its binding sites. Finally, our studies also revealed that TRPC6 regulates human clot retraction, as well as physiological hemostasis and thrombus formation, in mice. Taken together, our findings demonstrate, for the first time, that TRPC6 directly regulates TPR-dependent ROCE and platelet function. Moreover, these data highlight TRPC6 as a novel promising therapeutic strategy for managing thrombotic disorders.

  9. Endogenous nitric oxide protects against platelet-activating factor-induced bowel injury in the rat.

    Science.gov (United States)

    MacKendrick, W; Caplan, M; Hsueh, W

    1993-08-01

    Platelet-activating factor (PAF) causes bowel necrosis in animal models that is histologically identical to that seen in neonatal necrotizing enterocolitis, but little is known about endogenous mechanisms that might protect against PAF-induced bowel injury. We hypothesized that endogenous nitric oxide might represent such a protective mechanism. Adult male Sprague-Dawley rats were pretreated with 2.5 mg/kg NG-nitro-L-arginine methyl ester (L-NAME), a potent nitric oxide synthase inhibitor, and given injections of 1.5 micrograms/kg PAF 15 min later. Animals treated with normal saline placebo, L-NAME alone, and PAF alone were also studied. Superior mesenteric artery blood flow and blood pressure were continuously recorded. At the end of 2 h or upon death of the animal, hematocrit was measured and intestinal samples were taken for histologic examination and determination of myeloperoxidase activity, a measure of intestinal neutrophil content. Compared with animals given PAF alone, animals pretreated with L-NAME followed by PAF developed significantly worse bowel injury (median injury scores: 2.5 versus 0.5, p = 0.005), hemoconcentration (final hematocrit 65.2 +/- 2.0% versus 53.9 +/- 1.0%, p < 0.001), and intestinal myeloperoxidase activity (12.45 +/- 1.94 U/g versus 6.51 +/- 0.57 U/g, p < 0.01). The last two effects were further accentuated when 10 mg/kg L-NAME was given before PAF. Treatment with sodium nitroprusside, a nitric oxide donor, for 10 min before and after PAF administration reversed the effects of L-NAME. Animals pretreated with phenylephrine rather than L-NAME did not develop worse injury than animals treated with PAF alone despite comparable reductions in superior mesenteric blood flow before PAF treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

  10. Low molecular weight heparin alters porcine neutrophil responses to platelet-activating factor.

    Science.gov (United States)

    Kruse-Elliott, K T; Chaban, K; Grossman, J E; Tomasko, S; Kamke, C; Darien, B

    1998-09-01

    Because platelet-activating factor (PAF) is an important mediator of inflammation and heparin has anti-inflammatory effects, we hypothesized that low molecular weight heparin (LMWH) would inhibit PAF-induced activation and chemotaxis in porcine neutrophils. Citrated blood was obtained from pentobarbital-anesthetized pigs, and neutrophils were isolated over a 55%/65% Percoll gradient. The effect of LMWH on basal phorbol myristate acetate (PMA)-induced superoxide (SO) release, as well as its effect on PAF priming for PMA-induced SO release, were investigated. Additionally, the effect of LMWH on PAF-induced chemotaxis of neutrophils across transwell membranes was evaluated. Baseline SO release in response to PMA was .351+/-.046 nmol/10(6) cells/min, and this was decreased to .289+/-.034 nmol/10(6) cells/min by pretreatment with 50 U/mL LMWH. PMA-induced SO production was increased by .240+/-.042 nmol/10(6) cells/min when cells were primed with 10 microM PAF. This priming effect of PAF was reduced significantly by pretreatment of neutrophils with LMWH at 10 and 50 U/mL. Chemotaxis of neutrophils in response to 100 microM PAF was significantly decreased to 70.02+/-6.4% (n = 8) of the control response by pretreatment of cells with 50 U/mL LMWH. We conclude that LMWH has anti-inflammatory effects on porcine neutrophils, which includes attenuation of cell activation and chemotaxis in response to the lipid-derived inflammatory mediator, PAF.

  11. Mechanisms in bradykinin stimulated arachidonate release and synthesis of prostaglandin and platelet activating factor

    Directory of Open Access Journals (Sweden)

    D. Ricupero

    1992-01-01

    Full Text Available Regulatory mechanisms in bradykinin (BK activated release of arachidonate (ARA and synthesis of prostaglandin (PG and platelet activating factor (PAF were studied in bovine pulmonary artery endothelial cells (BPAEC. A role for GTP binding protein (G-protein in the binding of BK to the cells was determined. Guanosine 5-O- (thiotriphosphate, (GTPτS, lowered the binding affinity for BK and increased the Kd for the binding from 0.45 to 1.99 nM. The Bmax remained unaltered at 2.25 × 10-11 mole. Exposure of the cells to aluminium fluoride also reduced the affinity for BK. Bradykinin-induced release of ARA proved pertussis toxin (PTX sensitive, with a maximum sensitivity at 10 ug/ml PTX. GTPτS at 100 μM increased the release of arachidonate. The effect of GTPτS and BK was additive at suboptimal doses of BK up to 0.5 nM but never exceeded the levels of maximal BK stimulation at 50 nM. PTX also inhibited the release of ARA induced by the calcium ionophore, A23187. Phorbol 12-myristate 13-acetate or more commonly known as tetradecanoyl phorbol acetate (TPA itself had little effect on release by the intact cells. However, at 100 nM it augmented the BK activated release. This was downregulated by overnight exposure to TPA and correlated with down-regulation of protein kinase C (PKC activity. The down-regulation only affected the augmentation of ARA release by TPA but not the original BK activated release. TPA displayed a similar, but more potent amplification of PAF synthesis in response to both BK or the calcium ionophore A23187. These results taken together point to the participation of G-protein in the binding of BK to BPAEC and its activation of ARA release. Possibly two types of G-protein are involved, one associated with the receptor, the other activated by Ca2+ and perhaps associated with phospholipase A2 (PLA2. Our results further suggest that a separate route of activation, probably also PLA2 related, takes place through a PKC catalysed

  12. ExoU-induced vascular hyperpermeability and platelet activation in the course of experimental Pseudomonas aeruginosa pneumosepsis.

    Science.gov (United States)

    Machado, Gloria-Beatriz S; de Assis, Maria-Cristina; Leão, Robson; Saliba, Alessandra M; Silva, Mauricio C A; Suassuna, Jose H; de Oliveira, Albanita V; Plotkowski, Maria-Cristina

    2010-03-01

    To address the question whether ExoU, a Pseudomonas aeruginosa cytotoxin with phospholipase A2 activity, can induce hemostatic abnormalities during the course of pneumosepsis, mice were instilled i.t. with the ExoU-producing PA103 P. aeruginosa or with a mutant obtained by deletion of the exoU gene. Control animals were instilled with sterile vehicle. To assess the role of ExoU in animal survival, mice were evaluated for 72 h. In all the other experiments, animals were studied at 24 h after infection. PA103-infected mice showed significantly higher mortality rate, lower blood leukocyte concentration, and higher platelet concentration and hematocrit than animals infected with the bacterial mutant, as well as evidences of increased vascular permeability and plasma leakage, which were confirmed by our finding of higher protein concentration in bronchoalveolar lavage fluids and by the Evans blue dye assay. Platelets from PA103-infected mice demonstrated features of activation, assessed by the flow cytometric detection of higher percentage of P-selectin expression and of platelet-derived microparticles as well as by the enzyme immunoassay detection of increased thromboxane A2 concentration in animal plasma. Histopathology of lung and kidney sections from PA103-infected mice exhibited evidences of thrombus formation that were not detected in sections of animals from the other groups. Our results demonstrate the ability of ExoU to induce vascular hyperpermeability, platelet activation, and thrombus formation during P. aeruginosa pneumosepsis, and we speculate that this ability may contribute to the reported poor outcome of patients with severe infection by ExoU-producing P. aeruginosa.

  13. Thrombin-induced lysosomal exocytosis in human platelets is dependent on secondary activation by ADP and regulated by endothelial-derived substances.

    Science.gov (United States)

    Södergren, Anna L; Svensson Holm, Ann-Charlotte B; Ramström, Sofia; Lindström, Eva G; Grenegård, Magnus; Öllinger, Karin

    2016-01-01

    Exocytosis of lysosomal contents from platelets has been speculated to participate in clearance of thrombi and vessel wall remodelling. The mechanisms that regulate lysosomal exocytosis in platelets are, however, still unclear. The aim of this study was to identify the pathways underlying platelet lysosomal secretion and elucidate how this process is controlled by platelet inhibitors. We found that high concentrations of thrombin induced partial lysosomal exocytosis as assessed by analysis of the activity of released N-acetyl-β-glucosaminidase (NAG) and by identifying the fraction of platelets exposing the lysosomal-associated membrane protein (LAMP)-1 on the cell surface by flow cytometry. Stimulation of thrombin receptors PAR1 or PAR4 with specific peptides was equally effective in inducing LAMP-1 surface expression. Notably, lysosomal exocytosis in response to thrombin was significantly reduced if the secondary activation by ADP was inhibited by the P2Y12 antagonist cangrelor, while inhibition of thromboxane A2 formation by treatment with acetylsalicylic acid was of minor importance in this regard. Moreover, the NO-releasing drug S-nitroso-N-acetyl penicillamine (SNAP) or the cyclic AMP-elevating eicosanoid prostaglandin I2 (PGI2) significantly suppressed lysosomal exocytosis. We conclude that platelet inhibitors that mimic functional endothelium such as PGI2 or NO efficiently counteract lysosomal exocytosis. Furthermore, we suggest that secondary release of ADP and concomitant signaling via PAR1/4- and P2Y12 receptors is important for efficient platelet lysosomal exocytosis by thrombin.

  14. Protective Mechanisms of S. lycopersicum Aqueous Fraction (Nucleosides and Flavonoids on Platelet Activation and Thrombus Formation: In Vitro, Ex Vivo and In Vivo Studies

    Directory of Open Access Journals (Sweden)

    Eduardo Fuentes

    2013-01-01

    Full Text Available The purpose of this research was to investigate mechanisms of antiplatelet action of bioactive principle from S. lycopersicum. Aqueous fraction had a high content of nucleosides (adenosine, guanosine, and adenosine 5′-monophosphate by HPLC analysis. Also aqueous fraction presented flavonoids content. Aqueous fraction inhibited platelet activation by 15 ± 6% (P<0.05. Fully spread of human platelets on collagen in the presence of aqueous fraction was inhibited from 15 ± 1 to 9 ± 1 μm2 (P<0.001. After incubation of whole blood with aqueous fraction, the platelet coverage was inhibited by 55 ± 12% (P<0.001. Platelet ATP secretion and aggregation were significantly inhibited by the aqueous fraction. At the same concentrations that aqueous fraction inhibits platelet aggregation, levels of sCD40L significantly decreased and the intraplatelet cAMP levels increased. In addition, SQ22536, an adenylate cyclase inhibitor, attenuated the effect of aqueous fraction toward ADP-induced platelet aggregation and intraplatelet level of cAMP. Platelet aggregation ex vivo (human study and thrombosis formation in vivo (murine model were inhibited by aqueous fraction. Finally, aqueous fraction may be used as a functional ingredient adding antiplatelet activities (nucleosides and flavonoids to processed foods.

  15. Platelets as delivery systems for disease treatments

    OpenAIRE

    Shi, Qizhen; Montgomery, Robert R.

    2010-01-01

    Platelets are small, anucleate, discoid shaped blood cells that play a fundamental role in hemostasis. Platelets contain a large number of biologically active molecules within cytoplasmic granules that are critical to normal platelet function. Because platelets circulate in blood through out the body, release biological molecules and mediators on demand, and participate in hemostasis as well as many other pathophysiologic processes, targeting expression of proteins of interest to platelets an...

  16. Influence of platelet activating factor on expression of adhesion molecules in experimental pancreatitis

    Institute of Scientific and Technical Information of China (English)

    Hua Zhao; Ji-Wei Chen; Ya-Kui Zhou; Xue-Feng Zhou; Pei-Yun Li

    2003-01-01

    AIM: To determine whether Platelet activating factor (PAF)has a regulation role in the expression of adhesion moleculesand accumulation of neutrophils in a murine model of acutepancreatitis.METHODS: One hundred twenty-eight Kunming mice weredivided into four groups. Group 1 received 0.1 mi saline s.c.every hour for three hours (sham). Group 2 received cerulein(50 μg/kg dose s.c.) every hour for three hours. Group 3received AP and additional challenge of PAF (50 rg/kg inabsolute ethanol) (AP/PAF). Group 4 received AP, plustherapeutic treatment with GAB (25 mg dose i.p.) immediatelyafter the first challenge of cerulein (AP/GAB). Animals weresacrificed at 12 h after the first challenge of saline or cerulein.Adhesion molecules of pancreas were semi-quantified bySP methods. Standard assays were performed for serumamylase and myeloperoxidase activity (MPO) of pancreas.Histology of pancreas was scored in a blind manner. Watercontent of pancreas was also measured at the same time.RESULTS: Control pancreata showed negligible adhesionmolecule expression and neutrophil accumulation. Therewere evident adhesion molecules expression and neutrophilaccumulation in AP and AP/PAF compared with sham (P<0.05).AP/GAB had a lower level of adhesion molecules, neutrophils,and water content versus AP and AP/PAF (P<0.05). Histologyshowed a trend toward improvement in AP/GAB, but didnot reach statistical significance.CONCLUSION: PAF can induce the expression of adhesionmolecules that mediate neutrophil accumulation. The PAFantagonist reduces the expression of adhesion moleculesand the severity of inflammation when given immediatelyafter the induction of mild AP in mice. These results suggestthat PAF antagonism may be useful in the treatment of mildpancreatitis after its clinical onset.

  17. Human plasma platelet-activating factor acetylhydrolase. Oxidatively fragmented phospholipids as substrates.

    Science.gov (United States)

    Stremler, K E; Stafforini, D M; Prescott, S M; McIntyre, T M

    1991-06-15

    Human plasma platelet-activating factor (PAF) acetylhydrolase hydrolyzes the sn-2 acetyl residue of PAF, but not phospholipids with long chain sn-2 residues. It is associated with low density lipoprotein (LDL) particles, and is the LDL-associated phospholipase A2 activity that specifically degrades oxidatively damaged phospholipids (Stremler, K. E., Stafforini, D. M., Prescott, S. M., Zimmerman, G. A., and McIntyre, T. M. (1989) J. Biol. Chem. 264, 5331-5334). To identify potential substrates, we synthesized phosphatidylcholines with sn-2 residues from two to nine carbon atoms long, and found the V/k ratio decreased as the sn-2 residue was lengthened: the C5 homolog was 50%, the C6 20%, while the C9 homolog was only 2% as efficient as PAF. However, the presence of an omega-oxo function radically affected hydrolysis: the half-life of the sn-2 9-aldehydic homolog was identical to that of PAF. We oxidized [2-arachidonoyl]phosphatidylcholine and isolated a number of more polar phosphatidylcholines. We treated these with phospholipase C, derivatized the resulting diglycerides for gas chromatographic/mass spectroscopic analysis, and found a number of diglycerides where the m/z ratio was consistent with a series of short to medium length sn-2 residues. We treated the polar phosphatidylcholines with acetylhydrolase and derivatized the products for analysis by gas chromatography/mass spectroscopy. The liberated residues were more polar than straight chain standards and had m/z ratios from 129 to 296, consistent with short to medium chain residues. Therefore, oxidation fragments the sn-2 residue of phospholipids, and the acetylhydrolase specifically degrades such oxidatively fragmented phospholipids.

  18. Platelet-Activating Factor Antagonists Decrease Follicular Dendritic-Cell Stimulation of Human B Lymphocytes

    Directory of Open Access Journals (Sweden)

    Halickman Isaac

    2005-06-01

    Full Text Available Abstract Both B-lymphoblastoid cell lines and tonsillar B lymphocytes express receptors for platelet-activating factor (PAF. In lymph node germinal centres, B lymphocytes interact with follicular dendritic cells (FDCs, which present antigen-containing immune complexes to B lymphocytes. FDCs have phenotypic features that are similar to those of stromal cells and monocytes and may therefore be a source of lipid mediators. In this study, we evaluated the effects of the PAF antagonist WEB 2170 on the activation of tonsillar B lymphocytes by FDCs. FDCs were isolated from tonsils by Bovine Serum Albumin (BSA gradient centrifugation. After being cultured for 6 to 10 days, they were incubated with freshly isolated B cells in the presence or absence of the specific PAF receptor antagonist WEB 2170. B-lymphocyte proliferation was assessed by [3H]-thymidine incorporation, and immunoglobulin (Ig G and IgM secretion was assessed by enzyme-linked immunosorbent assay (ELISA. WEB 2170 (10-6 to 10-8 M inhibited [3H]-thymidine incorporation by up to 35% ± 3%. Moreover, the secretion of IgG and IgM was inhibited by up to 50% by WEB 2170 concentrations ranging from 10-6 to 10-8 M. There was no evidence of toxicity by trypan blue staining, and the addition of WEB 2170 to B cells in the absence of FDCs did not inhibit the spontaneous production of IgG or IgM. The effect of the PAF antagonist is primarily on B lymphocytes, as reverse transcription polymerase chain reaction detected little PAF receptor messenger ribonucleic acid (mRNA from FDCs. These data suggest that endogenous production of PAF may be important in the interaction of B lymphocytes with FDCs.

  19. Targeting factor VIII expression to platelets for hemophilia A gene therapy does not induce an apparent thrombotic risk in mice.

    Science.gov (United States)

    Baumgartner, C K; Mattson, J G; Weiler, H; Shi, Q; Montgomery, R R

    2017-01-01

    Essentials Platelet-Factor (F) VIII gene therapy is a promising treatment in hemophilia A. This study aims to evaluate if platelet-FVIII expression would increase the risk for thrombosis. Targeting FVIII expression to platelets does not induce or elevate thrombosis risk. Platelets expressing FVIII are neither hyper-activated nor hyper-responsive. Background Targeting factor (F) VIII expression to platelets is a promising gene therapy approach for hemophilia A, and is successful even in the presence of inhibitors. It is well known that platelets play important roles not only in hemostasis, but also in thrombosis and inflammation. Objective To evaluate whether platelet-FVIII expression might increase thrombotic risk and thereby compromise the safety of this approach. Methods In this study, platelet-FVIII-expressing transgenic mice were examined either in steady-state conditions or under prothrombotic conditions induced by inflammation or the FV Leiden mutation. Native whole blood thrombin generation assay, rotational thromboelastometry analysis and ferric chloride-induced vessel injury were used to evaluate the hemostatic properties. Various parameters associated with thrombosis risk, including D-dimer, thrombin-antithrombin complexes, fibrinogen, tissue fibrin deposition, platelet activation status and activatability, and platelet-leukocyte aggregates, were assessed. Results We generated a new line of transgenic mice that expressed 30-fold higher levels of platelet-expressed FVIII than are therapeutically required to restore hemostasis in hemophilic mice. Under both steady-state conditions and prothrombotic conditions induced by lipopolysaccharide-mediated inflammation or the FV Leiden mutation, supratherapeutic levels of platelet-expressed FVIII did not appear to be thrombogenic. Furthermore, FVIII-expressing platelets were neither hyperactivated nor hyperactivatable upon agonist activation. Conclusion We conclude that, in mice, more than 30-fold higher levels of

  20. The Autonomy Activity Status of Multinational Subsidiaries

    DEFF Research Database (Denmark)

    Dzikowska, Marlena; Gammelgaard, Jens; Jindra, Björn

    Research concerning the autonomy of subsidiaries has been concentrated on the possession of decision-making rights. Building on the definitional and empirical argumentation, we claim that so understood autonomy has a prospective character, is not equal to the implementation of actual actions (or...... lack of thereof) and neglects the issue of the scope of potential actions. This paper aims to fill in the current literature gap by offering a holistic stance in which we assert that subsidiaries can be meaningfully differentiated according to their levels of autonomy and corresponding actions. We base...... this argumentation on the findings of real option theory and competitive dynamics perspective, develop a typology specific to a subsidiary’s autonomy activity status (the position of a subsidiary in terms of its autonomy level confronted with the extent of actions taken in a corresponding area). We evaluate...

  1. The Autonomy Activity Status of Multinational Subsidiaries

    DEFF Research Database (Denmark)

    Dzikowska, Marlena; Gammelgaard, Jens; Jindra, Björn

    this argumentation on the findings of real option theory and competitive dynamics perspective, develop a typology specific to a subsidiary’s autonomy activity status (the position of a subsidiary in terms of its autonomy level confronted with the extent of actions taken in a corresponding area). We evaluate......Research concerning the autonomy of subsidiaries has been concentrated on the possession of decision-making rights. Building on the definitional and empirical argumentation, we claim that so understood autonomy has a prospective character, is not equal to the implementation of actual actions (or...... lack of thereof) and neglects the issue of the scope of potential actions. This paper aims to fill in the current literature gap by offering a holistic stance in which we assert that subsidiaries can be meaningfully differentiated according to their levels of autonomy and corresponding actions. We base...

  2. Preliminary evidence for a matrix metalloproteinase-2 (MMP-2)-dependent shedding of soluble CD40 ligand (sCD40L) from activated platelets.

    Science.gov (United States)

    Reinboldt, Stephan; Wenzel, Folker; Rauch, Bernhard H; Hohlfeld, Thomas; Grandoch, Maria; Fischer, Jens W; Weber, Artur-Aron

    2009-09-01

    Platelets are the major source of soluble CD40 ligand (sCD40L) in the blood. It has been demonstrated that CD40L is cleaved from the surface of activated platelets to release sCD40L. However, the enzyme involved in sCD40L shedding has not been identified yet. Using a panel of pharmacological inhibitors of serine, cysteine, aspartate, or metalloproteinases, preliminary evidence is presented for the hypothesis that matrix metalloproteinase-2 (MMP-2) might be the protease, primarily responsible for CD40L cleavage from platelet surface.

  3. Effects of TRA-418, a novel TP-receptor antagonist, and IP-receptor agonist, on human platelet activation and aggregation.

    Science.gov (United States)

    Miyamoto, Mitsuko; Yamada, Naohiro; Ikezawa, Shiho; Ohno, Michihiro; Otake, Atsushi; Umemura, Kazuo; Matsushita, Teruo

    2003-11-01

    [4-[2-(1,1-Diphenylethylsulfanyl)-ethyl]-3,4-dihydro-2H-benzo[1,4]oxazin-8-yloxy]-acetic acid N-Methyl-d-glucamine salt (TRA-418) has both thromboxane A2 (TP)-receptor antagonist and prostacyclin (IP)-receptor agonist properties. The present study examined the advantageous effects of TRA-418 based on the dual activities, over an agent having either activity alone and also the difference in the effects of TRA-418 and a glycoprotein alphaIIb/beta3 integrin (GPIIb/IIIa) inhibitor. TRA-418 inhibited platelet GPIIb/IIIa activation as well as P-selectin expression induced by adenosine 5'-diphosphate, thrombin receptor agonist peptide 1-6 (Ser-Phe-Leu-Leu-Arg-Asn-NH2), and U-46619 in the presence of epinephrine (U-46619+ epinephrine). TRA-418 also inhibited platelet aggregation induced by those platelet-stimulants in Ca2+ chelating anticoagulant, citrate and in nonchelating anticoagulant, d-phenylalanyl-l-prolyl-l-arginyl-chloromethyl ketone (PPACK). The TP-receptor antagonist SQ-29548 inhibited only U-46619+epinephrine-induced GPIIb/IIIa activation, P-selectin expression, and platelet aggregation. The IP-receptor agonist beraprost sodium inhibited platelet activation. Beraprost also inhibited platelet aggregation induced by platelet stimulants we tested in citrate and in PPACK. The GPIIb/IIIa inhibitor abciximab blocked GPIIb/IIIa activation and platelet aggregation. However, abciximab showed slight inhibitory effects on P-selectin expression. TRA-418 is more advantageous as an antiplatelet agent than TP-receptor antagonists or IP-receptor agonists separately used. TRA-418 showed a different inhibitory profile from abciximab in the effects on P-selectin expression.

  4. CdTe quantum dots induce activation of human platelets: implications for nanoparticle hemocompatibility

    Directory of Open Access Journals (Sweden)

    Samuel SP

    2015-04-01

    Full Text Available Stephen P Samuel,1 Maria J Santos-Martinez,2–4 Carlos Medina,2,3 Namrata Jain,1 Marek W Radomski,2,3 Adriele Prina-Mello,1,5 Yuri Volkov1,5 1Department of Clinical Medicine, Institute of Molecular Medicine, Trinity College Dublin, Dublin, Ireland; 2School of Pharmacy and Pharmaceutical Sciences, Trinity College Dublin, Dublin, Ireland; 3Trinity Biomedical Sciences Institute, Trinity College Dublin, Dublin, Ireland; 4School of Medicine, Trinity College Dublin, Dublin, Ireland; 5AMBER and CRANN, Trinity College Dublin, Dublin, Ireland Abstract: New nanomaterials intended for systemic administration have raised concerns regarding their biocompatibility and hemocompatibility. Quantum dots (QD nanoparticles have been used for diagnostics, and recent work suggests their use for in vivo molecular and cellular imaging. However, the hemocompatibility of QDs and their constituent components has not been fully elucidated. In the present study, comprehensive investigation of QD–platelet interactions is presented. These interactions were shown using transmission electron microscopy. The effects of QDs on platelet function were investigated using light aggregometry, quartz crystal microbalance with dissipation, flow cytometry, and gelatin zymography. Platelet morphology was also analyzed by phase-contrast, immunofluorescence, atomic-force and transmission electron microscopy. We show that the QDs bind to platelet plasma membrane with the resultant upregulation of glycoprotein IIb/IIIa and P-selectin receptors, and release of matrix metalloproteinase-2. These findings unravel for the first time the mechanism of functional response of platelets to ultrasmall QDs in vitro. Keywords: platelets, quantum dots, aggregometry, flow cytometry, zymography, quartz crystal microbalance, transmission electron microscopy

  5. Shape changes induced by biologically active peptides and nerve growth factor in blood platelets of rabbits.

    OpenAIRE

    Gudat, F; Laubscher, A.; Otten, U; Pletscher, A

    1981-01-01

    1 Nerve growth factor (NGF), substance P (SP) and thymopoietin all caused shape change reactions of rapid onset in rabbit platelets. NGF had the highest maximal effect, and SP the lowest EC50 (concentration causing half maximal shape change). The action of SP was reversible within 5 min, whereas that of NGF lasted for at least 1 h. A series of other peptides were inactive. 2 After preincubation of platelets with SP, a second application of SP no longer caused a shape change reaction, whereas ...

  6. Rho GTPases in platelet function.

    Science.gov (United States)

    Aslan, J E; McCarty, O J T

    2013-01-01

    The Rho family of GTP binding proteins, also commonly referred to as the Rho GTPases, are master regulators of the platelet cytoskeleton and platelet function. These low-molecular-weight or 'small' GTPases act as signaling switches in the spatial and temporal transduction, and amplification of signals from platelet cell surface receptors to the intracellular signaling pathways that drive platelet function. The Rho GTPase family members RhoA, Cdc42 and Rac1 have emerged as key regulators in the dynamics of the actin cytoskeleton in platelets and play key roles in platelet aggregation, secretion, spreading and thrombus formation. Rho GTPase regulators, including GEFs and GAPs and downstream effectors, such as the WASPs, formins and PAKs, may also regulate platelet activation and function. In this review, we provide an overview of Rho GTPase signaling in platelet physiology. Previous studies of Rho GTPases and platelets have had a shared history, as platelets have served as an ideal, non-transformed cellular model to characterize Rho function. Likewise, recent studies of the cell biology of Rho GTPase family members have helped to build an understanding of the molecular regulation of platelet function and will continue to do so through the further characterization of Rho GTPases as well as Rho GAPs, GEFs, RhoGDIs and Rho effectors in actin reorganization and other Rho-driven cellular processes. © 2012 International Society on Thrombosis and Haemostasis.

  7. Interactions between platelet activating factor and eicosanoids during endotoxic shock in anaesthetized pigs

    Directory of Open Access Journals (Sweden)

    T. Mózes

    1992-01-01

    Full Text Available The effects of platelet activating factor (PAF on eicosanoid release during endotoxic shock was investigated in anaesthetized pigs receiving 5 μg kg−1 Escherichia coli endotoxin (LPS into the superior mesenteric artery over a 60 min period, by measuring plasma levels of a variety of mediators. Fifteen of the 31 animals infused with LPS and not treated with BN 52021, a PAF receptor antagonist, died within 30 min after the commencement of LPS infusion (non-survivors, while the other 16 survived the experimental period of 3 h, though in a state of shock (survivors. No alterations were observed in plasma concentrations of eicosanoids in the non-survivors. A significant, though transient, increase in eicosanoid concentrations occurred only in the survivors. Treatment with BN 52021 (4 mg kg-1, i.v. injected 5 min prior to LPS infusion, failed to exert any effect on the survival rate. However, pretreatment with BN 52021 prevented circulatory collapse in the survivors and reduced the concentration of cyclooxygenase enzyme products, without affecting LTB4 release. Exogenous administration of PAF (0.01 μg kg−1 caused hypotension and increased TXB2 levels although 6-keto PGF1α and LTB4 concentrations were unchanged. The data suggest that prostanoid formation may be secondary to PAF release in circulatory collapse evoked by LPS infusion in survivors, and give further support to the suggestion that PAF prostanoid interaction is important during endotoxic shock. However, their role in early death seems to be negligible, indicating the importance of other mediators.

  8. Cholesterol synthesis inhibitors protect against platelet-activating factor-induced neuronal damage

    Directory of Open Access Journals (Sweden)

    Williams Alun

    2007-01-01

    Full Text Available Abstract Background Platelet-activating factor (PAF is implicated in the neuronal damage that accompanies ischemia, prion disease and Alzheimer's disease (AD. Since some epidemiological studies demonstrate that statins, drugs that reduce cholesterol synthesis, have a beneficial effect on mild AD, we examined the effects of two cholesterol synthesis inhibitors on neuronal responses to PAF. Methods Primary cortical neurons were treated with cholesterol synthesis inhibitors (simvastatin or squalestatin prior to incubation with different neurotoxins. The effects of these drugs on neuronal cholesterol levels and neuronal survival were measured. Immunoblots were used to determine the effects of simvastatin or squalestatin on the distribution of the PAF receptor and an enzyme linked immunoassay was used to quantify the amounts of PAF receptor. Results PAF killed primary neurons in a dose-dependent manner. Pre-treatment with simvastatin or squalestatin reduced neuronal cholesterol and increased the survival of PAF-treated neurons. Neuronal survival was increased 50% by 100 nM simvastatin, or 20 nM squalestatin. The addition of mevalonate restored cholesterol levels, and reversed the protective effect of simvastatin. Simvastatin or squalestatin did not affect the amounts of the PAF receptor but did cause it to disperse from within lipid rafts. Conclusion Treatment of neurons with cholesterol synthesis inhibitors including simvastatin and squalestatin protected neurons against PAF. Treatment caused a percentage of the PAF receptors to disperse from cholesterol-sensitive domains. These results raise the possibility that the effects of statins on neurodegenerative disease are, at least in part, due to desensitisation of neurons to PAF.

  9. Treatment with a histone deacetylase inhibitor, valproic acid, is associated with increased platelet activation in a large animal model of traumatic brain injury and hemorrhagic shock

    DEFF Research Database (Denmark)

    Dekker, Simone E; Sillesen, Martin; Bambakidis, Ted

    2014-01-01

    BACKGROUND: We have previously shown that resuscitation with fresh frozen plasma (FFP) in a large animal model of traumatic brain injury (TBI) and hemorrhagic shock (HS) decreases the size of the brain lesion, and that addition of a histone deacetylase inhibitor, valproic acid (VPA), provides...... synergistic benefits. In this study, we hypothesized that VPA administration would be associated with a conservation of platelet function as measured by increased platelet activation after resuscitation. MATERIALS AND METHODS: Ten swine (42-50 kg) were subjected to TBI and HS (40% blood loss). Animals were...... left in shock for 2 h before resuscitation with either FFP or FFP + VPA (300 mg/kg). Serum levels of platelet activation markers transforming growth factor beta, CD40 L, P-selectin, and platelet endothelial cell adhesion molecule (PECAM) 1 were measured at baseline, postresuscitation, and after a 6-h...

  10. The involvement of the CD40-CD40L pathway in activated platelet-induced changes in HUVEC COX-2 and PPARα expression.

    Science.gov (United States)

    Wu, Yan-qing; Chen, Xiao-shu; Chai, Jun-bing

    2012-06-01

    We aim to determine the extent of the CD40-CD40L pathway involvement in activated platelet-induced changes in human umbilical endothelial cells (HUVECs). Activated platelets were co-incubated with HUVECs in the presence or absence of CD40LmAb. HUVECs were also directly stimulated with rhCD40L. HUVEC endothelial cyclooxygenase 2 (COX-2) and peroxisome proliferator-activated receptor alpha (PPARα) expression was then assessed. To estimate COX-2 activity, PGE2 concentration was determined. PPARα activity was assessed using a nuclear factor activity kit. Co-incubation with activated platelets increased HUVEC COX-2 and PPARα mRNA expression (P HUVEC COX-2 mRNA and protein (P HUVEC COX-2 expression and activity partly through the CD40-CD40L pathway.

  11. Platelet adhesion, contact phase coagulation activation, and C5a generation of polyethylene glycol acid-grafted high flux cellulosic membrane with varieties of grafting amounts.

    Science.gov (United States)

    Fushimi, F; Nakayama, M; Nishimura, K; Hiyoshi, T

    1998-10-01

    Grafting of polyethylene glycol chains onto cellulosic membrane can be expected to reduce the interaction between blood (plasma protein and cells) and the membrane surface. Alkylether carboxylic acid (PEG acid) grafted high flux cellulosic membranes for hemodialysis, in which the polyethylene glycol chain bears an alkyl group at one side and a carboxyl group at the other side, have been developed and evaluated. PEG acid-grafted high flux cellulosic membranes with various grafting amounts have been compared with respect to platelet adhesion, the contact phase of blood coagulation, and complement activation in vitro. A new method of quantitating platelet adhesion on hollow-fiber membrane surfaces has been developed, which is based on the determination of lactate dehydrogenase (LDH) activity after lysis of the adhered platelets. PEG acid-grafted high flux cellulosic membranes showed reduced platelet adhesion and complement activation effects in grafting amounts of 200 ppm or higher without detecting adverse effects up to grafting amounts of 850 ppm. The platelet adhesion of a PEG acid-grafted cellulosic membrane depends on both the flux and grafting amounts of the membrane. It is concluded that the grafting of PEG acid onto a cellulosic membrane improves its biocompatibility as evaluated in terms of platelet adhesion, complement activation, and thrombogenicity.

  12. The Effect of PEI and PVP-Stabilized Gold Nanoparticles on Equine Platelets Activation: Potential Application in Equine Regenerative Medicine

    Directory of Open Access Journals (Sweden)

    Mateusz Hecold

    2017-01-01

    Full Text Available The aim of this work was to assess the effect of different stabilizing agents, for example, polyethylenimine (PEI and polyvinylpyrrolidone (PVP, on gold nanoparticles (AuNPs and their influence on equine platelet activation and release of particular growth factors. The gold nanoparticles were produced by chemical reduction of chloroauric acid. UV-Vis spectroscopy confirmed the presence of gold nanoparticles in investigated solutions. The AuNPs were incubated with whole blood at various concentrations. The morphology of platelets in PRP prepared from the blood incubated with AuNPs was characterized by scanning transmission electron microscopy, whereas the concentrations of growth factors and cytokines were evaluated by ELISA assays. The most promising results were obtained with equine platelets incubated with 5% AuNPs stabilized by PEI, which lead to secretion of bone morphogenetic protein 2 (BMP-2, vascular endothelial growth factor (VEGF, and fibroblast growth factor 1 (FGF-1 and simultaneously cause decrease in concentration of interleukin-1 alpha (IL-1α. The qRT-PCR confirmed ELISA test results. The incubation with 5% AuNPs stabilized by PEI leads to upregulation of BMP-2 and VEGF transcripts of mRNA level and to downregulating expression of interleukin-6 (IL-6. Obtained data shed a promising light on gold nanoparticle application for future regenerative medicine application.

  13. All-trans-Retinoic Acid Ameliorated High Fat Diet-Induced Atherosclerosis in Rabbits by Inhibiting Platelet Activation and Inflammation

    Directory of Open Access Journals (Sweden)

    Birong Zhou

    2012-01-01

    Full Text Available Background. All-trans-retinoic acid (atRA is effective for many proliferative diseases. We investigated the protective effects of atRA against atherosclerosis. Methods. Rabbits were randomly allocated to receive basal diet or an HFD for 4 weeks. HFD group then received rosuvastatin (3 mg/day, atRA (5 mg/kg/day, or the same volume of vehicle, respectively, for next 8 weeks. Results. HFD group showed increases in plasma lipids and aortic plaque formation. P-selectin expression and fibrinogen binding on platelets or deposition on the intima of the aorta also increased significantly as did the levels of TNF-α, IL-6, and fibrinogen in plasma. After 8 weeks of treatment with atRA, there was a significant decrease in plasma lipids and improvement in aortic lesions. AtRA also inhibited the expression of P-selectin and fibrinogen binding on platelets and deposition on the intima of the aorta. Conclusion. AtRA can ameliorate HFD-induced AS in rabbits by inhibiting platelet activation and inflammation.

  14. An overview of platelet indices and methods for evaluating platelet function in thrombocytopenic patients

    DEFF Research Database (Denmark)

    Vinholt, Pernille Just; Hvas, Anne-Mette; Nybo, Mads

    2014-01-01

    in thrombocytopenia. Flow cytometry, platelet aggregometry and platelet secretion tests are used to diagnose specific platelet function defects. The flow cytometric activation marker P-selectin and surface coverage by the Cone and Plate[let] analyser™ predict bleeding in selected thrombocytopenic populations...

  15. Platelet Activation Determines Angiopoietin-1 and VEGF Levels in Malaria : Implications for Their Use as Biomarkers

    NARCIS (Netherlands)

    Brouwers, Judith; Noviyanti, Rintis; Fijnheer, Rob; de Groot, Philip G.; Trianty, Leily; Mudaliana, Siti; Roest, Mark; Syafruddin, Din; van der Ven, Andre; de Mast, Quirijn

    2013-01-01

    Introduction: The angiogenic proteins angiopoietin (Ang)-1, Ang-2 and vascular endothelial growth factor (VEGF) are regulators of endothelial inflammation and integrity. Since platelets store large amounts of Ang-1 and VEGF, measurement of circulation levels of these proteins is sensitive to platele

  16. Dauricoside, a new glycosidal alkaloid having an inhibitory activity against blood-platelet aggregation.

    Science.gov (United States)

    Hu, S M; Xu, S X; Yao, X S; Cui, C B; Tezuka, Y; Kikuchi, T

    1993-10-01

    Dauricoside (1), a new glycosidal alkaloid, was isolated from the rhizomes of Menispermum dauricum DC. along with dauricine (2), daurisoline (3), dauriporphine (4), menisporphine (5), and 6-O-demethylmenisporphine (6), and its structure was determined by means of spectroscopic methods. Compounds 1, 2, and 3 inhibited blood-platelet aggregation induced by adenosine 5'-diphosphate (ADP).

  17. Hydroxytyrosyl alkyl ether derivatives inhibit platelet activation after oral administration to rats.

    Science.gov (United States)

    Muñoz-Marín, Javier; De la Cruz, José Pedro; Reyes, José Julio; López-Villodres, Juan Antonio; Guerrero, Ana; López-Leiva, Inmaculada; Espartero, José Luis; Labajos, María Teresa; González-Correa, José Antonio

    2013-08-01

    The low lipophilicity of hydroxytyrosol (HT) has motivated efforts to synthesize homologous series with better lipid solubility, such as the ethers, which are more lipophilic than HT. Because HT inhibits platelet aggregation, the aim of the study was to assess the possible anti-platelet effect of five HT ether derivatives (ethyl, butyl, hexyl, octyl and dodecyl) after oral administration to rats. Whole blood collagen-induced platelet aggregation and calcium-induced thromboxane B2 (TxB2), aortic 6-keto-prostaglandin F1α (6-keto-PGF1α) and nitrites+nitrates, plasma concentration of lipid peroxides (TBARS) and red blood cell content of reduced glutathione (GSH) were measured. The administration of 20 mg/kg/day inhibited platelet aggregation, TxB2 and TBARS in a non-linear manner related to the length of the carbon chain, with a cut-off effect in the hexyl derivative. Aortic nitrite and red blood cell GSH production were also increased. The aortic production of 6-keto-PGF1α was unaltered except in the group treated with the dodecyl derivative. The administration of 50 mg/kg/day showed a similar pharmacodynamic profile but without the non-linear effect. In conclusion, HT ethers, especially the hexyl derivative, are a potential alternative to hydroxytyrosol, and their effect merits additional research to determine their role in the prophylaxis of vascular disease.

  18. Platelet function alterations in dengue are associated with plasma leakage

    NARCIS (Netherlands)

    Michels, M.; Alisjahbana, B.; Groot, P.G. de; Indrati, A.R.; Fijnheer, R.; Puspita, M.; Dewi, I.M.; Wijer, L. van de; Boer, E.M. de; Roest, M.; Ven, A.J. van der; Mast, Q. de

    2014-01-01

    Severe dengue is characterised by thrombocytopenia, plasma leakage and bleeding. Platelets are important for preservation of endothelial integrity. We hypothesised that platelet activation with secondary platelet dysfunction contribute to plasma leakage. In adult Indonesian patients with acute dengu

  19. Staphylococcal β-Toxin Modulates Human Aortic Endothelial Cell and Platelet Function through Sphingomyelinase and Biofilm Ligase Activities

    Science.gov (United States)

    Herrera, Alfa; Kulhankova, Katarina; Sonkar, Vijay K.; Dayal, Sanjana; Klingelhutz, Aloysius J.; Salgado-Pabón, Wilmara

    2017-01-01

    ABSTRACT Staphylococcus aureus causes many infections, such as skin and soft tissue, pneumonia, osteomyelitis, and infective endocarditis (IE). IE is an endovascular infection of native and prosthetic valves and the lining of the heart; it is characterized by the formation of cauliflower-like “vegetations” composed of fibrin, platelets, other host factors, bacteria, and bacterial products. β-Toxin is an S. aureus virulence factor that contributes to the microorganism’s ability to cause IE. This cytolysin has two enzymatic activities: sphingomyelinase (SMase) and biofilm ligase. Although both activities have functions in a rabbit model of IE, the mechanism(s) by which β-toxin directly affects human cells and is involved in the infectious process has not been elucidated. Here, we compared the in vitro effects of purified recombinant wild-type β-toxin, SMase-deficient β-toxin (H289N), and biofilm ligase-deficient β-toxin (H162A and/or D163A) on human aortic endothelial cells (HAECs) and platelets. β-Toxin was cytotoxic to HAECs and inhibited the production of interleukin 8 (IL-8) from these cells by both SMase and biofilm ligase activities. β-Toxin altered HAEC surface expression of CD40 and vascular cell adhesion molecule 1 (VCAM-1). HAECs treated with β-toxin displayed granular membrane morphology not seen in treatment with the SMase-deficient mutant. The altered morphology resulted in two possibly separable activities, cell rounding and redistribution of cell membranes into granules, which were not the result of endosome production from the Golgi apparatus or lysosomes. β-Toxin directly aggregated rabbit platelets via SMase activity. PMID:28325766

  20. Whole blood flow cytometry measurements of in vivo platelet activation in critically-Ill patients are influenced by variability in blood sampling techniques.

    Science.gov (United States)

    Rondina, Matthew T; Grissom, Colin K; Men, Shaohua; Harris, Estelle S; Schwertz, Hansjorg; Zimmerman, Guy A; Weyrich, Andrew S

    2012-06-01

    Flow cytometry is often used to measure in vivo platelet activation in critically-ill patients. Variability in blood sampling techniques, which may confound these measurements, remains poorly characterized. Platelet activation was measured by flow cytometry performed on arterial and venous blood from 116 critically-ill patients. We determined how variability in vascular sampling site, processing times, and platelet counts influenced levels of platelet-monocyte aggregates (PMA), PAC-1 binding (for glycoprotein (GP) IIbIIIa), and P-selectin (P-SEL) expression. Levels of PMA, but not PAC-1 binding or P-SEL expression, were significantly affected by variability in vascular sampling site. Average PMA levels were approximately 60% higher in whole blood drawn from an arterial vessel compared to venous blood (16.2±1.8% vs. 10.7±1.2%, psampling site, processing times, and platelet counts influence levels of PMA, but not PAC-1 binding or P-SEL expression. These data demonstrate the need for rigorous adherence to blood sampling protocols, particularly when levels of PMA, which are most sensitive to variations in blood collection, are measured for detection of in vivo platelet activation. Copyright © 2011 Elsevier Ltd. All rights reserved.

  1. Combined blockade of ADP receptors and PI3-kinase p110β fully prevents platelet and leukocyte activation during hypothermic extracorporeal circulation.

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    Stefanie Krajewski

    Full Text Available Extracorporeal circulation (ECC and hypothermia are used to maintain stable circulatory parameters and improve the ischemia tolerance of patients in cardiac surgery. However, ECC and hypothermia induce activation mechanisms in platelets and leukocytes, which are mediated by the platelet agonist ADP and the phosphoinositide-3-kinase (PI3K p110β. Under clinical conditions these processes are associated with life-threatening complications including thromboembolism and inflammation. This study analyzes effects of ADP receptor P(2Y(12 and P(2Y(1 blockade and PI3K p110β inhibition on platelets and granulocytes during hypothermic ECC. Human blood was treated with the P(2Y(12 antagonist 2-MeSAMP, the P(2Y(1 antagonist MRS2179, the PI3K p110β inhibitor TGX-221, combinations thereof, or PBS and propylene glycol (controls. Under static in vitro conditions a concentration-dependent effect regarding the inhibition of ADP-induced platelet activation was found using 2-MeSAMP or TGX-221. Further inhibition of ADP-mediated effects was achieved with MRS2179. Next, blood was circulated in an ex vivo ECC model at 28°C for 30 minutes and various platelet and granulocyte markers were investigated using flow cytometry, ELISA and platelet count analysis. GPIIb/IIIa activation induced by hypothermic ECC was inhibited using TGX-221 alone or in combination with P(2Y blockers (p<0.05, while no effect of hypothermic ECC or antiplatelet agents on GPIIb/IIIa and GPIbα expression and von Willebrand factor binding was observed. Sole P(2Y and PI3K blockade or a combination thereof inhibited P-selectin expression on platelets and platelet-derived microparticles during hypothermic ECC (p<0.05. P(2Y blockade alone or combined with TGX-221 prevented ECC-induced platelet-granulocyte aggregate formation (p<0.05. Platelet adhesion to the ECC surface, platelet loss and Mac-1 expression on granulocytes were inhibited by combined P(2Y and PI3K blockade (p<0.05. Combined blockade of P

  2. Experimental Antithrombotic Effect of Garlic Varieties Measured by a Global In Vitro Test of Platelet Reactivity and Spontaneous Thrombolytic Activity

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    Yoshinobu Ijiri

    2016-06-01

    Full Text Available Prevention of arterial thrombotic diseases has high priority over treatment in developed countries. Unsuitable life style such as inappropriate quality and quantity of daily diet is known to increase the risk for acute thrombotic events, while a regular diet with proven antithrombotic effects might be beneficial in preventing the disease. The present study was undertaken as a part of a series of research in screening vegetables, fruits and medicinal herbs for antithrombotic activity by animal models of thrombosis. In the present study the effects of fifteen garlic varieties (accessions on platelet reactivity and spontaneous (endogenous thrombolytic activity were measured ex vivo from saline-diluted rat blood by the Global Thrombosis Test (GTT. All accessions showed antithrombotic activity but the activity varied between accessions. The heat stable antithrombotic activity was dominantly due to inhibition of platelet reactivity to high shear stress while the spontaneous thrombolytic activity was not affected. These findings suggest that daily intake of garlic as part of an antithrombotic diet may be beneficial for the prevention of arterial thrombotic disorders.

  3. The influence of Rubus idaeus and Rubus caesius leaf extracts on platelet aggregation in whole blood. Cross-talk of platelets and neutrophils.

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    Dudzinska, Dominika; Bednarska, Katarzyna; Boncler, Magdalena; Luzak, Boguslawa; Watala, Cezary

    2016-07-01

    Recently, polyphenols have gained attention as potential natural cardioprotective therapeutics, due to their antiplatelet, anti-inflammatory and anticoagulant activity. Species belonging to the genus Rubus sp. have been reported to be a source of polyphenolic compounds with antioxidative proprieties and beneficial biological activities. This study investigates the effects of leaf extracts obtained from red raspberry (Rubus idaeus L.) and European dewberry (Rubus caesius L.) on the reactivity of blood platelets. In ADP-stimulated blood, raspberry and dewberry extracts (15 µg/ml) markedly decreased platelet surface membrane expression of activated GPIIbIIIa receptor by 16% and 21%, respectively (P raspberry and by 38-55% for dewberry, P raspberry and dewberry leaf extracts considerably modulated blood platelet reactivity in whole blood: they influenced blood platelet aggregation, possibly via the modulation of the redox status dependent on the oxidative activity of neutrophils.

  4. Assessment of the influence of the inflammatory process on the activation of blood platelets and morphological parameters in patients with ulcerative colitis (colitis ulcerosa

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    Halina Kemona

    2011-04-01

    Full Text Available Ulcerative colitis (colitis ulcerosa is a non-specific inflammatory bowel disease of unknown etiology. The symptoms which are observed in the course of ulcerative colitis are: an increase in the number of leukocytes and blood platelets, an increase in the concentration of IL-6 and anemia. Blood platelets are the key element, linking the processes of hemostasis, inflammation and the repair of damaged tissues. Activation of blood platelets is connected with changes in their shape and the occurrence of the reaction of release. P-selectin appears on the surfaces of activated blood platelets and the concentration level of soluble P-selectin increases in the blood plasma. The aim of this study was to define whether the increased number of blood platelets in patients with ulcerative colitis accompanies changes in their activation and morphology. A total of 16 subjects with ulcerative colitis and 32 healthy subjects were studied. Mean platelet count, morphological parameters of platelets and MPC were measured using an ADVIA 120 hematology analyzer. Concentrations of sP-selectin and IL-6 in serum were marked by immunoassay (ELISA. MPC, concentration of sP-selectin and IL-6 were significantly higher in subjects with ulcerative colitis compared to those in the healthy group. There was a decrease of MPV in patients with ulcerative colitis, which is statistically significant. Chronic inflammation in patients with ulcerative colitis causes an increase in the number of blood platelets, a change in their morphology and activation. Decreased MPV value reflects activation and the role blood platelets play in the inflammatory process of the mucous membrane of the colon. A high concentration of sP-selectin, which is a marker of blood platelet activation, demonstrates their part in the inflammatory process. The increase in the concentration of sP-selectin correlated positively with the increase in concentration of IL-6. This is why it may be a useful marker

  5. Platelet-activating factor in the enteric nervous system of the guinea pig small intestine.

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    Wang, Guo-Du; Wang, Xi-Yu; Hu, Hong-Zhen; Fang, Xiu-Cai; Liu, Sumei; Gao, Na; Xia, Yun

    2006-11-01

    Platelet-activating factor (PAF) is a proinflammatory mediator that may influence neuronal activity in the enteric nervous system (ENS). Electrophysiology, immunofluorescence, Western blot analysis, and RT-PCR were used to study the action of PAF and the expression of PAF receptor (PAFR) in the ENS. PAFR immunoreactivity (IR) was expressed by 6.9% of the neurons in the myenteric plexus and 14.5% of the neurons in the submucosal plexus in all segments of the guinea pig intestinal tract as determined by double staining with anti-human neuronal protein antibody. PAFR IR was found in 6.1% of the neurons with IR for calbindin, 35.8% of the neurons with IR for neuropeptide Y (NPY), 30.6% of the neurons with IR for choline acetyltransferase (ChAT), and 1.96% of the neurons with IR for vasoactive intestinal peptide (VIP) in the submucosal plexus. PAFR IR was also found in 1.5% of the neurons with IR for calbindin, 51.1% of the neurons with IR for NPY, and 32.9% of the neurons with IR for ChAT in the myenteric plexus. In the submucosal plexus, exposure to PAF (200-600 nM) evoked depolarizing responses (8.2 +/- 3.8 mV) in 12.4% of the neurons with S-type electrophysiological behavior and uniaxonal morphology and in 12.5% of the neurons with AH-type electrophysiological behavior and Dogiel II morphology, whereas in the myenteric preparations, depolarizing responses were elicited by a similar concentration of PAF in 9.5% of the neurons with S-type electrophysiological behavior and uniaxonal morphology and in 12.0% of the neurons with AH-type electrophysiological behavior and Dogiel II morphology. The results suggest that subgroups of secreto- and musculomotor neurons in the submucosal and myenteric plexuses express PAFR. Coexpression of PAFR IR with ChAT IR in the myenteric plexus and ChAT IR and VIP IR in the submucosal plexus suggests that PAF, after release in the inflamed bowel, might act to elevate the excitability of submucosal secretomotor and myenteric musculomotor

  6. In vitro anti-inflammatory and anti-coagulant effects of antibiotics towards Platelet Activating Factor and thrombin

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    Demopoulos Constantinos A

    2011-07-01

    Full Text Available Abstract Background Sepsis is characterized as a systemic inflammatory response that results from the inability of the immune system to limit bacterial spread during an ongoing infection. In this condition the significant mediator of inflammation Platelet Activating Factor (PAF and the coagulant factor thrombin are implicated. In animal models, treatment with PAF-antagonists or co-administration of antibiotics with recombinant-PAF-Acetylhydrolase (rPAF-AH have exhibited promising results. In order to examine the putative anti-inflammatory and/or antithrombotic interactions between antibiotic treatment used in sepsis with PAF and/or thrombin, we studied the in vitro effects of these compounds towards PAF or/and thrombin related activities and towards PAF basic metabolic enzymes. Methods We assessed the inhibitory effect of these drugs against PAF or thrombin induced aggregation on washed rabbit platelets (WRPs or rabbit Platelet Reach Plasma (rPRP by evaluating their IC50 values. We also studied their effect on Cholinephosphotransferase of PAF (PAF-CPT/Lyso-PAF-Acetyltransferase (Lyso-PAF-AT of rabbit leukocytes (RLs,